Metformin and Risk For Vitamin B12 Deficiency

Metformin (brand names Glucophage, Glucophage XR, Fortamet, Riomet, Glumetza, and others) is a popular and highly effective oral diabetes drug used to help manage Type 2 diabetes. This drug works by lowering the amount of glucose made by the liver and by making the body’s cells more sensitive to insulin. Metformin also has some other beneficial effects in that it may help lower blood lipid, or fat, levels (cholesterol and triglycerides) and can, in some people, promote a small amount of weight loss.


Metformin can be used with other diabetes pills and with insulin. Side effects of taking metformin are relatively rare, the most common being bloating, nausea, and diarrhea, all of which are temporary. Some people shouldn’t take metformin, including people with kidney disease, liver disease, or congestive heart failure, for example, because of an increased risk of a potentially fatal condition called lactic acidosis.

In recent years, there’s been some concern over the risk of vitamin B12 deficiency in people who take metformin. Vitamin B12 (also known as cyanocobalamin or cobalamin) plays many important roles in the body, such as keeping your blood cells and nervous system in tip top shape. There’s also some evidence that vitamin B12 may help prevent heart disease and possibly even Alzheimer disease (the jury is still out on this one). This vitamin is found primarily in animal foods, such as beef, seafood, eggs, and dairy products, which is why some vegetarians are at risk for a B12 deficiency. Elderly people are often at risk for deficiency as well, due to problems with absorption from the gastrointestinal tract. Symptoms of B12 deficiency include certain types of anemia, neuropathy, memory loss, confusion, and even dementia.

So, why would taking metformin possibly put you at risk for a B12 deficiency? According to some studies, between 10% and 30% of people who take metformin on a regular basis have some evidence of decreased B12 absorption. Researchers aren’t quite sure why this happens. In a study recently published in the October 9 issue of the journal Archives of Internal Medicine,155 Chinese people with Type 2 diabetes taking metformin were identified as having a B12 deficiency, regardless of factors such as age or body weight. The study found that the longer a person had been taking metformin and the higher his daily dose of the drug, the greater his risk of developing B12 deficiency.

The authors of the study advocate consideration of vitamin B12 deficiency screening for people who take metformin. While this screening isn’t routine, it’s worth it to have a talk with your health-care provider to see if you’re at risk for deficiency, especially if you’ve been taking metformin for several years or take a high dose. Also, if you have any of the symptoms of B12 deficiency mentioned above, particularly those related to neuropathy (numbness, pain, or tingling in your hands or feet), be sure to let your physician know. He or she can check the level of vitamin B12 in your blood.

Vitamin B12 deficiency can be treated with either oral, injected, or inhaled forms of B12. Some people, such as strict vegetarians or the elderly, may need to take supplements or receive injections on a regular basis. B12 is found in most multivitamin supplements, so it doesn’t hurt to take a multivitamin as a safeguard. However, avoid taking a B12 supplement unless your doctor has prescribed them. Too much vitamin B12 may be harmful, and B12 can also interact with certain medicines. Always let your health-care team know about all medicines and supplements that you’re taking at each visit.

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  • Gabriel

    I m using Vitamin b12Patch to overcome the lack of energy. I was experiencing Fatigue and was feeling stressed out. So I started using this patch. It is required to apply on specified body part. Not required to be injected into the body.

  • Carla

    You can not take to much B12. Its water soluable and any extra is eliminated by your kidneys through urination.

  • acampbell


    It’s true that vitamin B12 is relatively harmless, as it is a water-soluble vitamin. However, there have been a very small handful of studies linking B12 excess with prostate cancer. B12 injections can cause allergic reactions and mild diarrhea in a small number of people. Taking large doses of B12 along with vitamin C may lead to nosebleeds. The point is that taking large doses of this or any other vitamin, mineral or supplement probably isn’t a good without medical supervision.

  • sh10492

    What information has Bristol Myers Squibb provided to physicians on this matter, if any. Are they taking any efforts to proactively getting this information into the hands of us who take this drug?

    Also, I have read that normal tests for B12 levels may not disclose that patients are deficient in B12 as it does not disclose that the problem may be malabsorption.

    Are there any studies that indicate Metformin decreases the bodies ability to properly utilize B12 even if it is at adequate levels? Sort of like being insulin resistant except being B12 resistant.

    Finally, is Bristol Myers making any proactive attempt to have physicians test specifically for B12 in patient with a long history of metformin use?

  • acampbell

    Hi sh10492,

    I’m not aware of any particular campaign on the part of Bristol Myers to inform physicians on the potential risk of B12 deficiency with metformin use. However, there is mention of this risk in the package insert for Glucophage/Glucophage XR, and it’s recommended in the PI that those at risk for deficiency be screened at 2-3 year intervals. Apparently testing for methylmalonic acid (MMA)over blood B12 levels is recommended by some, but it’s use is still somewhat controversial in the medical community. One theory is that metformin may interfere with B12 absorption; however, it appears that supplementation with 1000-1200 mg of calcium can limit this interference with B12 absorption. As I mentioned in my posting, it’s important for anyone taking metformin, particularly long-term, to talk to his or her healthcare provider about the potential risk for B12 deficiency and the steps one can take to prevent this from happening.

  • sh10492

    Thank you for the commenting on my questions.

    I find the package insert to be insufficient. It indicates that paitients should be “predisposed” and testing “may be useful”.

    Given the rates of 30% B12 deficiency it would seem (from a layman’s point of view) that taking the medication predisposes one to the deficiency and knowledge of the deficiency would be MORE than useful.

  • msmith

    I was just wondering if it is harmful to take a vitamin B-12 plus prenatal vitamins daily. I am not pregnant, I just thought it would be good to take the prenatal vitamin for the extra vitamins.

  • acampbell

    Hi msmith,

    There’s very little risk in taking a B-12 supplement. However, I’m wondering why you’re taking a prenatal vitamin, given that you’re not pregnant. Prenatal vitamins contain more folic acid, iron and calcium than regular multivitamins. Unless it’s been advised by your physician, I’d suggest switching to a regular multivitamin and focus on getting the remainder of your vitamins and minerals from food sources.

  • sh10492

    I have now been taking Vitamin B12 for 24 days. In that time my insulin requirement has gone from 60-65 units to 15-20 daily. I still take Metformin and now take 2000mcg of B12.

    My energy level has skyrocketed.It seems my mental cognition and memory have also improved.

    Unfortunately many of the symptoms of B12 depletion mimic diabetes complications. I have been suffering from this depletion for at least 4 years and just learned to cope until I hit a wall and suffered many health consequences. It got so bad that in December I had decided to claim my disability insurance as I had no hope of maintaining a 40 hour work week.

    Four days after taking Vitamin B12 I began to feel better. Within a week I felt “Good” for the first time in months.

    Lets get the word out about this! Too many people are suffering and the drug companies have done nothing to alert patients and physicians of consequences of metformin and glucophage for long term users.

  • acampbell

    Hi sh10492,
    Thanks for sharing this – very encouraging! Hopefully this will encourage people who take metformin to have a discussion with their provider about a possible risk of B12 depletion.

  • C.J.COOK

    I have diabetes type two but was not diagnosed long after it should have been
    i can not eat because i do not digest food
    and so i thought if i could take B-12 Sublin
    gual which would go under the tongue and dis
    dissolve and quickly enters the blood-stream.

  • acampbell

    Hi C.J.,
    You can certainly take B12 sublingually. You may want to check with your physician as to what dose would be approriate for you. For people who haven’t had a source of B12 for a while, a starting dose might be 2000 micrograms daily for a couple of weeks, for example, then tapering down to once a week. For people with deficiencies or other medical issues, B12 injections might be needed. So talk with your physician as to what method and dose would be best for you.

  • YL

    HI ,,,,
    2000 MCG OF B12…
    WHAT is the right dose……


  • acampbell

    Hi YL,
    You can take B6 and B12 together. Also, furosemide may slightly deplete these two vitamins, so it’s okay to take them with this medication. You may want to take your vitamins with or after a meal. However, you’re taking fairly high doses of B6; the RDA is 1.3-1.5 mg for women, and the upper limit is 100 mg/day. Too much B6 can be harmful. Also, unless you’re deficient or have a malabsorption disorder, you don’t need 2000 mcg of B12 (anywhere from 1-25 mcg would be okay). I’d suggest you talk with your physician about doses that are best for you.

  • YL

    thank you so much for you advice….
    you really gave me a peace of mind….

  • Karen

    This is such an interesting discussion. I was diagnosed with Pernicious anemia as my B12 levels were very low. My Mother and her six sisters also had pernicous anemia as does my older (and only) sister. I am having a b12 injection monthly, but I really feel I need it three weekly as the last week I am so lethargic I can barely move. I have type 2 diabetes and am taking 2000 mg of Metformin daily. I had never heard of the link between the two.

  • HoneyNZ

    Hi, I took Metformin in 2005 and stopped taking it after 18 months without telling my physician, I was prescribed to take a total of 2500mg/day for my PCOS, that’s 1000mg at breakfast, 500mg at lunch and 100mg at dinner. I was advised by my physician to take it on a gradually increasing dose which I did. The reason why I stopped taking it was due to being sick of urgently needing to go the toilet every after meal and it’s always been loose. After reading your blog, I realised that I may be lacking in B12 when I was taking Metformin as I also get fatigued easily and I became forgetful. The last time I took Metformin was 2 years ago. Now that I just saw another physician, he advised me to start taking Metformin again as it will help my PCOS, but this time, I was only prescribed to take 500mg three times a day. The next time I see my physician I will ask him to check my B12 levels.

  • kashif

    I have started getting White hair rapidly. I surfed the web and got the info that its most likely due the deficicency of Vitamin B12. 1). Can you kindly discuss this please? No matter how brief your kind suggestions are. 2). Are vitamin B12 tablets are under non-subscription drugs? i mean should i need to have Doctor’s letter to buy these pills? 3). which one is the best product for these pills? Will highly appreciate for your kind suggestions. Thanks!

  • acampbell

    Hi kashif,
    I’m not a hair expert, but please keep in mind that there are many causes of white or graying hair, including family history, age, gender and illness. Pernicious anemia, resulting from a lack of vitamin B12, may also be a cause. However, you should discuss this possibility with your physician before concluding that you’re deficient in B12 and before you start taking B12 supplements. B12 is available without a doctor’s prescription, but, again, please discuss your concerns with your physician to rule out other possible causes of your white hair.

  • tenorsaxgyrl

    I was on Metformin a few years ago and had to stop…after 3 months, I was still vomiting and having horrid bowel movements. My doctor retested me and stated that my previous doctor (the one that prescribed it) might have been over cautious as I had no sign of high blood sugar or triglycerides. However, because of PCOS they recommend that I might want to start taking it again as I am trying to conceive. What do you think? Can and should I take this while taking the prenatal vitamins? I worry about the constant nausea I had previously.

  • acampbell

    Hi tenorsaxgyrl,
    Gastrointestinal side effects occur in up to 1/3 of people who take metformin. Given your previous side effects with this drug, you should talk to your provider about ways that you might prevent them from occuring again, or at least minimize them. Some suggestions are to start with a very low dose and gradually build up; take your metformin with meals; and limit rich, fatty meals. I’m not aware of metformin interacting with prenatal vitamins. You can always try metformin again and see what happens. Obviously, if you still get extreme side effects such as nausea, vomiting and diarrhea, metformin probably isn’t for you.

  • live4fitness

    when they check for the b12 deficiency do they do a CBC or a specific B12 test?

  • acampbell

    Hi live4fitness,

    Vitamin B12 levels are measured, often along with folate (another B vitamin) as a separate blood test. A CBC, or complete blood count, may indicate the presence of large red blood cells, which would then prompt your provider to order a separate B12 blood test.

  • superwoman

    I took metformin for about a year and it also gave me constant diarrhea. Because of the diarrhea my sodium and magnesium are low and haven’t been able to correct the levels yet. I also have a B-12 deficiency, i have been taking shots for almost a year and still my levels are low. My doctor recently said that was enough of the metformin because it seem to do more harm than good, she now has me on a diabetes med called januvia. I have been on this medication for about 3 wks and I haven’t had has much diarrhea. I wondered if the diarrhea from the metformin is what caused my B-12 to be low also.





  • acampbell

    Hi Fay,
    No, taking metformin with vitamin B1, which is thiamine, does not cause lactic acidosis. Lactic acidosis is a very serious condition whereby lactic acid builds up in the blood. Symptoms include loss of appetite, nausea, vomiting and abdominal pain. It most often occurs in people with kidney or liver disease, or in people who have tests involving injected dyes, or after surgery. If you take metformin and are scheduled for any kind of radiologic test or surgery, you may need to temporarily stop taking your metformin, so check with your physician for instructions.

  • acampbell

    Hi superwoman,
    It’s possible that the diarrhea you’ve had caused a B12 deficiency; however, it’s probably more likely that the metformin itself was responsible. Fortunately, your diarrhea has resolved and hopefully your B12 levels will return to normal soon.

  • meridith

    i was recently diagnosed with pcos and am taking metformin (850x daily) along with synthroid for low thyroid. We hope to try to have kids in the next year or so and I have been taking pre-natal vitamins. I saw your previous post about them, should I not be taking them with metformin and synthroid?

  • acampbell

    Hi Meridith,
    You might try taking your prenatal vitamins separately from your metformin. Also, it’s probably a good idea not to take your vitamins with your Synthroid, as the iron may decrease the absorption and action of your thyroid hormone.

  • MG

    I just turned 35 and in the past year have been having multiple issues including muscle tenderness/tingling, lack of focus, inabilty to sleep the night and light headedness. I may have had these issue in the past off and on, but recently I have been more focused on them as I get older. My sister told me I may be B12 deficient, since we are both Type A+/O+ blood type. Her doctor told her that this combination traditionally is deficient in B12. Does this make sense or is it a possibility?

  • Jillybean

    I am 72 years old and am a type 2 diabetic. For 5 years I have been taking Metformin 500 x 3 times per day. Tingling/numbness in my feet, pains in legs and ankles also swelling (possible odema) weight gain and general tiredness when walking and I have made an appointment with my GP to discuss these problems re possibility of a B12 deficiency. Apart from my age, would you agree these symptoms could be linked to this type of deficiency? Any comments would be so appreciated. Thank You.

  • acampbell

    Hi Jillybean,

    Please realize that I’m not a physician and cannot diagnose anyone. However, some of your symptoms could be consistent with a B12 deficiency, including the tingling and numbness in your legs, and your fatigue. Weight gain and swelling are usually not linked with a B12 deficiency. I’m glad to hear that you’re going to discuss your symptoms and possible causes with your physician.

  • acampbell

    Hi MG,
    I’m not aware of a particular blood type being linked to B12 deficiency, but I suppose that could be a possibility. The more common causes of B12 deficiency include insufficient intake, malabsorption disorders, such as Crohn’s disease, certain types of abdominal surgery, parasites, pernicious anemia and aging. You really should discuss your symptoms with your physician to rule out other possible causes for your symptoms.

  • rosdonald

    I have been experiencing Menieres symptoms for the last five years. In the past two years, I have noticed a rapid progression of vertigo, ataxia, a feeling of falling, and positional problems. Two days ago I started taking a protein powder and vitamin supplement and yesterday I had the first vertigo free day in years. I began to wonder if I might have a vitamin deficiency, and this morning have discovered a possible link between my metformin, vitamin b12 deficiency, and ataxia. I may be grasping for straws, but do you think that there might be a connection?


  • acampbell

    Hi Rose,
    Not being an expert in Meniere’s, I’m a little skeptical that the improvement in your symptoms is due to the vitamin and protein supplements that you’ve started, particularly after being on both for such a short time. I’m not aware of specific vitamins that have been linked with Meniere’s. But, if you’ve been on metformin for a while, it’s possible that you’re deficient in B12. Ask your provider at your next appointment to check your B12 level. Also, I’d suggest you go easy with the protein powder; most people don’t need additional protein, unless they are ill, have undergone surgery, or follow a strict eating regimen that might restrict protein.

  • meridith

    Thank you so much for your response, just to clarify….does that mean I should not take prenatal vitamins at all with metformin and synthroid or just that I should space it out and take the vitamins at a different time in the day than when I take my meds?

  • acampbell

    Hi meridith,

    I’d recommend you take your vitamins at a separate time from your medications. It’s fine for you to continue with your vitamins AND your meds – just take them apart from each other.

  • libelula

    Thank you so much for this discussion! I was wondering if the metformin/B12 deficiency link was as strong when taking Janumet? I have not been tested for B12 deficiency (but plan on discussing that with my doctor soon) but have been suffering from nausea and lightheadedness for the past week. I’ve been on 50-1,000 mg of Janumet twice a day for 2 months now, and was on metformin for 1 month before that. Also, I had my son 5 months ago and I’m not sure if that’s even a factor, if my body is not quite back to normal yet.

  • acampbell

    Hi libelula,
    It’s certainly possibly that a B12 deficiency could occur when taking Janumet (a combination of Januvia and metformin), although you haven’t been taking it for all that long, so a deficiency is probably unlikely at this point. Your nausea could be due to the metformin. Please contact your physician soon to discuss your symptoms and possible causes.

  • Dorothy

    I’m 55 yo & have been taking Metformin for almost 10 yrs. I’ve often complained to Drs. about leg pain & feeling exhausted. She tested thyroid – it was ok. Now test came back with low iron & B12. I read about the link to Metformin & asked. She said she hasn’t seen it clinically. Wants colonoscopy to check for internal bleeding. Why won’t Drs. listen to patients?

  • acampbell

    Hi Dorothy,
    Doctors have so much information to keep up with and stay on top of, and it’s very likely that your doctor wasn’t aware of the link between metformin and vitamin B12. She’s being thorough, though, in ordering a colonoscopy for you. What’s often helpful for communicating effectively with healthcare professionals about a particular issue is to bring in a copy of an article that explains the issue; that way, they can do their own “research” (even though it’s frustrating when they didn’t listen to you in the first place!).

  • bertk523

    Question – i have seen some information that says taking calcium can reverse the b12 absorbtion issue caused by metformin. have you heard that? is there a recommended dose of calcium, or should i check with my doc. thanks. i got my first b12 shot today for b12, anemia issues. i have taken metformin for 10 years.

  • acampbell

    Hi bertk523,

    There is some evidence that taking 1200 mg of calcium (as a supplement) may help limit the effect of metformin on B12 levels. It’s something you could consider trying, although it’s not a bad idea to discuss with your physician, first.

  • Joanna

    I’ve been taking Metformin for 10 years. My current dosage is 1000 mg 2x per day. (the max) About 3 months ago I was diagnosed with a B12 deficiency. It must have been very low, because I had to get a shot once a week for a month, then 1 a month since. I told my physician about the study linking metformin with B12 deficiency and she had never heard of it. I asked about changing to a different med, but I was told that we’ve tried everything else but Insulin. I dont want to go that route unless really necessary If I continue to take the Metformin and the shots will my B12 go back to normal?

  • acampbell

    Hi Joanna,
    Depending on the extent of your B12 deficiency, it probably will take at least several weeks or even a couple of months to restore your levels. You need to keep on top of your levels until they return back to normal. Ask your physician to periodically check your B12 levels after that, as well. In the meantime, make sure that your diet contains plenty of B12 (taking a multivitamin is a good idea if you’re not already doing so).

  • fwman

    Hi, I have been taking metformin for some ten years now .The veterans lab told me my B-12 count was low ,and to take 1000MCG tablets as soon as possible . I have been taking the B-12 for f4ive monthe noe ,a blood test indicated t

  • acampbell

    Hi fwman,

    I’m not sure what your question is – it looks like it got cut off…?

  • fwman

    Hi I am a user of metformin for ten years now.
    I am seventy eight ,The veterans admin, told me my b-12 was very low ,and to start takeing100MCG of B_12. Blood test lately said my B-12 was fine .Should i keep on taking the B_12. I feel fine at this time .What do you think? Thanks for your time ,Buck Carpenter

  • acampbell

    Hi fwman,

    It’s good to hear that your B12 levels are back to normal. I’d suggest you talk to your physician about whether you should continue taking the supplement. 100 mcg is a large dose, which you needed in order to correct your low B12 level. You probably don’t need this large a dose anymore, but your physician might suggest that you continue with a lower dose or even take a multivitamin. Also, make sure you know why your level was low in the first place so that you can prevent it from dropping again.

  • Maria

    My mother has been on Metformin for 4 years now. She is 75 years old. Today,during my mother’s primary physician appointment I had mentioned to him that I have found that Metformin causes a vitamin B12 deficiency when I researched it on the Internet. I was really looking for any solutions to my mother’s other problem of having a burning feeling from below her knees to her feet (both legs). She is also having memory loss, fatigue, balance problems, constipation, loss of appetite, etc. When I mentioned that since her memory doctor suggested that she have her vitamin B12 checked and found that she was deficient, I told him that Metformin had to be the cause. He never heard of it! He also checked some small book on his desk to see if he can look it up himself. I also had left a message for my mother’s Endocronologist. He just gave me a call and guess what? He never heard of it either. I told him to look it up on the Internet. I had also told him that her memory doctor found that she was deficient in vitamin B12 and so I had to do my own investigation. I did ask for another kind of diabetic pill that my mother could take so she can get off of Metformin. Her primary doctor prescribed glimepiride. Does anyone know if this medication can also cause the vitamin B12 deficiency? I just can’t believe that I had to be my own doctor to help my mother. Everyone is so used to listen to their primary doctors, then when you need to go to a specialist, like getting a second opinion for your primary, you can’t even trust that they are going to be the experts in what they say they are experts it. If this is what our American doctors constantly do, experiment on us, then I suggest that we become our own doctors, do our own research and go back to the natural way of healing our bodies because we are fed up of being ginny pigs for the drug companies and the physicians. I just hope my mother’s B12 levels come back up since she has been getting a monthly shot and also taking 2500 mcg supplement every day. Please also let me know if the 2500 mcg is ok. Thank you.

  • acampbell

    Hi Maria,
    To my knowledge, glimepiride doesn’t lead to a vitamin B12 deficiency. I believe that a typical oral dose of B12 to correct deficiency is between 1000 and 2000 mcg daily for 1-2 weeks. The dose that your other currently takes is probably fine for now but she shouldn’t need to stay on that indefinitely, especially since she’s also getting a B12 injection. Speak to her primary care physician about the dosing schedule for correcting the deficiency and then a maintenance dose.

  • worried about mom

    This information is very helpful. My mom has had diabetes for 17 years now. She has been taking metformin for a while. She recently was told she had Vit b12 deficiency and that she needs to have injections to correct this. My question is, why would the doctor order injections and not oral medication? Do the injections work more efficiently?
    Thank you in advance for you help.

  • acampbell

    Hi worried about mom,

    Oral B12 supplements can be given to correct a B12 deficiency, but the dose would have to be pretty large in order to do so. For this reason, injections are usually given for deficiencies. Also, there is some concern that people may not take the full oral dose, whereas one would receive the right amount in an injection. Up to 30% of adults older than age 50 have difficulty absorbing vitamin B12 in the digestive tract due to decreased levels of hydrochloric acid, so taking an oral B12 supplement would be of little use in this situation (this is a reason that many older adults get B12 injections). Finally, some other medications can interfere with B12 absorption in the digestive tract, including some used to treat peptic ulcer disease and gastroesophageal reflux. So, it’s a good thing that your mother is getting B12 injections.

  • Peacock

    A couple of weeks ago I experienced raw sore red tongue. Just all of a sudden it came on. I knew I hadn’t eaten anything different. It continued to get worse. With a few sores appearing inside my mouth. So I started doing research online to find out what is causing this. I do this before I see my Doctor on things. Sure enough I came across the depletion of B12 issue connected to taking Metformin. I mentioned this finding to a Doctor I work with in a clinic. and He said it wouldn’t be that…it had to be something else. I knew he was wrong. So I went out and got B12 2000mcg. Started taking it and in 3 days my tongue was back to normal. Also I noticed no more stinging and numbing on top of my feet…which I was associating with my Type 2. I also made sure that I told that Doctor I work with what I did and how it helped and this would be good info in case another diabetic expereinced it. I also told him to google it to find out I was right.
    I will see my regular Doctor in May and tell him about this experience.

  • gl52

    I’ve been taking metphomin for about 8-10 years. I’ve had diabetis for 23 years and also take insulin 70/30. I also suffer from gastro problems since I was a child and take medication for acid reflex. Recently my Endo prescribed Byetta because I’m my pancreas are becoming insulin resistant where I require a lot of insulin. I had to be admitted into the hospital for observation because I was having fast heart beats and fainthing spells. They did all types of test and the only thing the doctor found was low levels of B12 that he could not understand why. He sent me home with a prescription of B12 shots but never mentioned anything about metphormin. I am now taking 600mg of calcium when I take my metphormin. Does that sound ok.

  • acampbell

    HI gl52,

    Unfortunately, many healthcare providers aren’t aware of the link between taking metformin and vitamin B12 deficiency. However, the good news is that you’ll be getting B12 shots and taking calcium. Be sure to follow up with your doctor and find out when you should get your B12 level checked and what the result it.

  • Deb

    Thank you so much for this post. I have been taking Metformin 2000 mg per day for 8 years now for type 2 diabetes. I had lots of tingling and pain in my feet that was diagnosed as neuropathy. I got tested recently for B12 deficiency and started getting B12 shots. What a wonderful difference. The constant pain in my feet has stopped and I have more energy. The plan is to continue to get the injections and test again to make sure the B12 in my body is increasing.

  • Deb

    Hi GL52, i have a similar history to yours and also have taken metformin for 8 years, but I want to address your comment about Byetta. I also had fast heartbeat and fainting when I took Byetta. My gastroenterologist believed that Byetta was increasing my gastro problems because it slows the emptying of the stomach. After discussing it with my endroconlogist, I stopped taking Byetta and started using Humalog along with some 70/30 in the am and pm and the heartbeats and fainting got better. I still found that my B12 was low and as I mentioned in the last note, I started getting B12 injections and the neuropathy pain in my feet has subsided.

  • kate donegan

    My mum has been suffering a fairly rapid weakness in her legs and now 3 months later and barely able to walk and using a frame she was told she had motor neurone disease. The family were devestated. As far as we know this diagnosis stands however she was told a few days ago that she has Vit B12 deficiency and after reading about it on the web, the symptoms fit all of hers. She is on metformin and has been for about 5 years now but we never knew of this side effect and it seems neither did her doctor who was still puzzled as to the cause of this neuropathy. We are all very hopeful that with injections of Vit B12 her weakness will begin to resolve. I wish we had known earlier about this and even more so I wish her general practioner did too.

  • acampbell

    Hi Kate,

    I certainly hope that the B12 injections help to resolve your mother’s leg weakness. It’s great that you informed her doctor about the link between metformin and B12 deficiency, too.

  • Kim

    hi – i just wanted to share my experience and knowledge regarding b12 deficiencies.

    pernicious anemia in and of itself is not the same as a b12 deficiency, although a b12 deficiency is a symptom of pernicious anemia and is often the determining factor for the diagnosis of pernicious anemia. while the differences are subtle, a b12 deficiency alone has less to do with blood (anemia) than with the body’s inability to absorb the vitamin from the GI tract. (for example, the CBC test would actually come back as normal, but the b12 would test low – b12 deficiency. if the CBC came back abnormal AND there was a b12 deficiency, then that points to pernicious anemia because it is blood related.) it hardly makes a difference, really, but it is interesting to know exactly why one has a b12 deficiency – malabsorption or anemia. the treatment would be the same – most likely b12 injections.

    i have been on metformin 500mg 2x/daily for over 4 years to treat PCOS. i am not trying to get pregnant, but the other conditions that PCOS can cause (facial hair, insulin resistance, Syndrome X) are be helped with this medication.

    two years ago, after a surge of migraines and fibromyalgia-seeming symptoms, i was diagnosed as having a severe b12 deficiency – which my doctor and i both feel were the culprit of the increased migraines and nerve pain. my doctor did not make the connection with the metformin use at first (apparently it is a rather new discovery/link), but after discussion he advised that the small dose i am taking would probably not be the cause. in the end, we decided together that i get a great deal of benefit from metformin, and the b12 injections are not too much of hardship, so i am staying on metformin and now having one b12 shot a month (in the beginning it was one every week, then as the level in my body began to rise and sustain, the frequency has been decreased). to date, my body has not yet been able to retain a sufficient level of b12, thus the continued injections.

    also, while taking a b12 supplement is a good idea, remember that if malabsorption is the problem, an oral tablet of b12 will not be absorbed by the body anyway – a sublingual tablet has more of a chance since it is not absorbed through the GI tract, but passes into the bloodstream under the tongue. injections put the b12 right into bloodstream so it is immediately available to the body. additionally, the dosing available in an injection is considerably higher than what an OTC vitamin supplement can provide, so it may be necessary to maintain injections to get the b12 level up, then try to supplement with a pill.

    i am not a doctor, but i am a healthcare professional. this post is to be taken as discussion only and not any medical diagnosis or advice. talk to your doctor if you have concerns about your b12 deficiency, pernicious anemia and/or your concerns about metformin use.


  • Jay


    I’ve been diagnosed as a type 2 diabetic 8-18-09. I just turned 40yrs old in August..

    I started on 500mg’s of metformin and my level was at 353 and came down to the 200’s in 3 weeks. My doctor says I’m not down far enough. So they upped my dosage to 2 times a day and then 3 times a day. I was wondering about this aching and pains in my legs and abdominal area. I also have the tingling in my fingers and numb big toes.. I’m glad I read this postings cause now I think I see why. I went out and purchased b-12 (1000mgs)yesterday and started … hopefully it makes me feel better and kills these aches and numbness. My level is at 125 now since the 3X a day metformin. I really have trouble sleeping because of the uncomfortable aches and pains.. I take many hot baths to soothe the pain and then it comes right back,, temporary relief is better than nothing …whew.. Hopefully the b-12 helps out. I’ve only taken one dose. Maybe in a couple days-weeks.. I’ll be back with a feel better story of my own.. wish me luck

  • acampbell

    Hi Jay,

    At the American Diabetes Association Scientific Sessions this past June, researchers presented a study that looked at vitamin B12 deficiency in people with Type 2 diabetes who were taking metformin for at least one year. They found that more than 75% of the metformin users who had low B12 levels also had peripheral neuropathy. There’s not enough evidene from this study to conclude that the low B12 levels caused or contributed to the neuropathy, but it does reinforce the need for people who take metformin to have their vitamin B12 levels checked. I do hope you’ve told your doctor about your pain and the fact that you’re taking a B12 supplement. Pain is always a cause for concern and you should let your doctor know to rule out other possible causes. And, if you truly are deficient in vitamin B12, your doctor can recommend the appropriate B12 dose for you (I assume you’re taking 1000 micrograms [mcg], not milligrams [mg]).

  • Jay

    Yes.. Micrograms is correct. I will let the doctor know today. I haven’t contacted her yet. Its crazy when you will try anything to feel better these days. I’ve never been the one who visits the doctor’s office often. Now i’m always there. I’ll go ahead and stop taking the vitamins til I get word from my doctor. Thanks for the feedback

  • Pat

    I take an extra strenght Great Earth “TNT” multivitamin which contains 75 mg of all the B vitamins including 75 mg of B12. Not 75 mcg, but 75 mg. The daily percentage contained in this vitamin for B12 is listed on the bottle as 1,250%. Is this OK to take without side affects? All the B’s are in the 2-3,000% daily range with this multivitamin. Is this normal for a multi-vitamin?

  • acampbell

    Hi Pat,

    I’m not really sure why you need to take such a potent multivitamin. You’re getting way more than the recommended daily allowance of these vitamins, and there’s not a lot of evidence that taking this much is helpful. Large doses of vitamin B12 are likely not harmful, but more than 100 mg per day of vitamin B6 may lead to nerve damage, and 50 mg or more of niacin may cause flushing. There’s also some evidence (not conclusive yet, though) coming out that more than 1000 micrograms per day of folic acid may increase the risk of cancer. While you’re not getting this amount in the vitamin, you are (I’m assuming) getting these vitamins from food sources, too. In general, taking a multivitamin that provides no more than 100 to 150% of the RDA or Daily Value of vitamins and minerals is your best bet.

  • Deb

    I was recently tested and my B12 was extremely low. I have been using metformin for 8 years. I am now taking a B12 shot on a regular basis.

  • Don

    I have been Type II diabetic since July, 2006 (of course, I could have had the condition for some time by that time, but for various reasons I don’t think so). I have been on 1000mg of Metformin twice daily since then (I now also take a low dose of Glymepiride once daily). Until recently, I was between 6.0-7.0 A1C every three months. At diagnosis, I suffered from discomforting intermittent (mostly at night) diabetic peripheral neuropathy (feet tingling/pain).

    In a comprehensive blood screening I had back then, I noted a low B12 level, so I self- medicated with an oral supplment and got my B12 level back to normal over time (as indicated by further blood work), though, of course, I didn’t connect the B12 deficiency with any particular problem, and my endocinologist did not make the connection between low B12 and any problem I was having (the low B12 level wasn’t even discussed).

    Once my B12 level was back to normal, my neuropathy declined to infrequent. Desiring to take no more meds than reasonably necessary, I stopped taking the oral B12 supplement probably about a year ago and have not had a blood test within that time that screened for B12 deficiency.

    Three months ago, suddenly, my A1C was 7.5; two weeks ago, it was 8.3. I weigh 190, down from 230, but my endocrinologist wants me to lose 25 pounds more (at 165, I would be quite thin). Since I’m having a difficult time getting there, he prescribed Byetta. I have been giving myself the shots now for about a week.

    Today, I began hearing my heartbeat in my ears very prominently and continuously. In my case, this condition is known as subjective bilateral pulsatile tinnitus. It is annoying at best, debilitating at worst. I have been experiencing it on a minor (and quite tolerable) level for several years.

    Tonight, I am very thankful to have found your blog because, from it, I now know that my Metformin quite likely has caused my B12 deficiency to return, and I have learned that the incrased heart rate I have been feeling is quite likely the result of the Byetta.

    I will seek to begin B12 shots tomorrow, and I will discontinue the Byetta because I cannot tolerate the increased heart rate causing this terrible increase in the pulsatile tinnitus.

    This blog entry is to thank you for your work and concern, and it is meant to add to the discussion in hopes of being helpful to other readers.

    Thanks. Don

  • vijayakumar


    i am taking 1500 mg of Metformin daily for the past 6 months . Before that i was taking Dianel 5 mg , but discontinued as i was going Hypo ( 60–70 ).with Metformin i have found 7 Kg loss of weight over last 6 months .I have developed Nueropathy of feet and also i have problem with Eye squeezing on one side and feeling numbness in my left side of my Head .My Hemoglbin levels were before 15.5 but now came to 13.8 and my average FBS raised to 125 from 110 ( H1bac 5.0 — 5.8 ) and i have no problems of stomuch upsets .
    can you suggest or diagnose my problem . Is it necessary to take Nerobion ( B complex with B12 )
    Thanks in advance and regards

    Posted by vijayakumar | Jan 12, 2010 at 4:27 am

  • acampbell

    Hi vijayakumar,

    Unfortunately, I really can’t diagnose you, particularly since I’m not a physician and this isn’t the right forum for diagnosis. You really should discuss your symptoms with your physician to find out what’s causing them and how they can be treated.

  • Jaz

    I just started taking Metformin for the begining stages of PCOS. I take quite a few OTC supplements to counteract nutritional defeciencies. I’m also fairly active. I am considering taking Creatine to help with my energy levels during workouts and I’m hoping you can tell me if there’s any side effects or interactions I should be concerned about with Creatine and Metformin. Thanks.

  • acampbell

    Hi Jaz,

    I wasn’t able to find much information on taking metformin and creatine simultaneously. There’s limited data on the safety of creatine, however. You should avoid this supplement if you have kidney or liver disease. If you do take creatine, be on the lookout for muscle pain, leg pain, dizziness, and irregular heart beat. Also, in theory, creatine could interact with insulin or other glucose-lowering drugs, and caution is advised if taking creatine with diuretics and other drugs that could damage kidneys, such as ibuprofen. Please let your physician know, too, if you do start taking this supplement.

  • LMO

    I have had Type 2 diabetes for the past 7 years and have been taking 2000mg of Metformin for the past 5 1/2 years. About 4 years ago, I started with tingling and “vibrating” in my feet and legs, which progressed over time up to my thighs. Over the past year or so, I have gotten to where my whole body feels like it is shaking all over, even though you cannot see it. It happens mostly at night, but often makes me feel like I am “dying”. I have had fogginess and also forgetfulness, and I have had to hold onto the railing to climb up the steps from the basement. I am ONLY 40 years old!!! All this time, my PCP and my Endocrinologist kept telling me it was neuropathy from my diabetes. My HBA1C ranges from 7.0-7.4. I believed them. Recently, I really thought I was losing my mind and couldn’t figure out why I was so tired and had all these progressing symptoms, so my PCP did order a B12 test. I was borderline low and started last week taking B12 injections of 1000mcg. They were ordered only monthly. Within 1 day I felt much more energy and mental clarity and within a week, my neuropathy symptoms were at least 50% improved. Last night, on my 8th day after my first injection, my symptoms came back very severe. I had a horrible night and had to call the PCP to get him to order my shots increased to weekly. I then took another one this morning and I already feel some better, but I definitely don’t want to feel again like I felt last night! I’m still not sure if I should continue my Metformin, or if I should just go to increased insulin dosage. ( I take Lantus at night.) I will discuss this tomorrow with my Endocrinologist. Thank you for your blog. I am grateful for the information here!

  • Donna

    I have been taking Metformin for 12 yrs, in addition I use Prandin and inject Byetta 10 mcg 2x day and Humulin N at night. Recently my Endo decided in addition to checking my thyroid levels and low Vit. D levels he would check B-12 and Folic Acid. He asked me if I ate green leafy veggies and fruit, which I do daily at just about every meal. He mentioned that my B-12 was ok but that I was very deficient in Folic Acid. I realize this forum is mostly on the subject of B-12, but my Endo had no answer for me about possible drug interactions as I am on a statin and 3 Blood pressure meds too. Can you possibly answer me about whether Metformin or Byetta could possibly be a reason for this?

  • acampbell

    Hi Donna,

    Folic acid is one of the B vitamins that works with vitamin B12 to form red blood cells and DNA; it’s also needed for tissue growth and for cells to work. The form of folic acid in food is called folate. Folic acid deficiency can occur due to a number of reasons, including: being pregnant, having an eating disorder, not eating enough food sources of folate, alcoholism, kidney disease, and certain types of gastrointestinal diseases. Also, certain mediciness may block the absorption of folic acid, including anticonvulsants, methotrexate, drugs for ulcerative colitis, oral contraceptives, triamterene (a blood presure drug), and metformin! So, it’s possible that your metformin is triggering your deficiency (not sure if you take any of the other meds I listed, above, either). The RDA for folate is 400 micrograms for adult women; however, your doctor may prescribe a folic acid supplement to correct your deficiency.

  • Donna

    Thank you for answering, and your time.

  • phillipuk

    Undiagnosed type 2 diabetes for at least 4-5 years prior to 2007. At one time my symptons all of the ones posted plus others including eye and hearing problems and external reorbtion dental problems and poor healing and open to simple infrections becoming serious, also confusion and lack of concentration.I was offered anti-depressants which I declined and held out for a diagnosis of exclusion of diabetes plus a glucose tolerance test which was not done as a routine only HBA1c
    Been taking Metformin for 3 years at 500x 2 daily
    Just been informed that my B12 is 180 (low) but now have lumbar spinal compression problems : are these mutually exclusive or have mutual causation?
    Yours is a very interesting site from this side of the pond too.
    Phillip UK

  • acampbell

    Hi Phillip,

    I’m not aware of any connection between vitamin B12 and/or metformin with spinal compression problems. From what little I know of spinal compression, much has to do with normal wear and tear as well as aging. However, since I’m not a physician, I’m not the best person to answer this for you. Talk with your physician about this, if you haven’t done so already.

  • sue

    I have PCOS and am on metformin 500 mg 3 times a day so 1 pill with each meal. I was able to have 3 wonderful kids so now that fertility is not an issue anymore do I need to stay on the metformin?

    Also I get kidney stones and am tired all the time…and then there is the tingling in the wrists and feet especially upon waking or working out…which most doctors thought was related to poor circulation or carpel tunel syndrome.

    My tests on the thyroid all came back fine and I don’t know how I would have carpel tunnel syndrome as I do not do repetitive work with my hands so I am going to try the b 12. The question is will affect kidney stone issues either for the better and halt their creation or for the worse in making them grow or continue to crop up faster than normal.

    I read the posts on the calcium issue and the uroligist doesn’t want me to take any other calcium supplements and has recommended that I cut back and stop taking the calcium I was taking and drink more things with natural lemon in it for the kidney stone issues.

    I know you are not a doctor and cannot tell me definitively what to do, but any guidance is appreciated. It seems like somehow all of these things are linked but so far most doctors are telling me NO they really are not.

  • acampbell

    Hi Sue,

    To answer your question about metformin, the answer is “it depends.” Metformin is used primarily to decrease insulin resistance, so even though fertility is no longer an issue for you, insulin resistance may still be. Find out what your glucose, cholesterol, and blood pressure numbers are and discuss with your doctor. It’s possible that you’re deficient in vitamin B12 and maybe even B6, which could be responsible for your carpal tunnel symptoms. Your doctor should be able to check your vitamin levels and then prescribe doses to correct any deficiencies. As for your kidney stones, treatment depends on the type of stone you have. If you’re excreting high levels of calcium in your urine (measured by a 24 hour urine collection), then it makes sense not to overdo the calcium (but you should still get between 1000–1200 mg per day, ideally from food sources). Also, cutting back on sodium and animal protein and drinking plenty of fluids may help prevent kidney stones, too. I’m not aware of any link between taking vitamin B12 and an increased risk for kidney stones.

  • acampbell

    Hi Sue,

    If you’re interested, I read a short article in The New York Times about kidney stones regarding the use of fruit juices to decrease kidney stone formation. The citrate in citrus fruit juices can reduce the formation of calcium oxalate stones (the most common type). Lemonade or lemon juice is often recommended for preventing kidney stones, but a study from 2006 found that drinking 3 cups of orange juice per day did a better job at increasing the acidity of the urine (and hence, likely, stone formation). The catch, though, is that oj is pretty high in carbohydrate and calories. So, if you are using lemon juice, make sure it’s unsweetened or sweetened with a nonnutritive sweetener. You might also try True Lemon, which is crystallized lemon juice (also available in orange and lime) to add to foods and beverages without adding calories or carbohydrate.

  • Vanessa

    Recentyl I had problems with my balance when walking and standing. It got really bad to ehre sometimes I felt like I was going to fall. My primary care doctor referred me to a neurologist. The neurologist had me take a blood test to see if my B12 levels were low and they were 167. I have been taking B12 shots for about two weeks and my energy level has increased but my balance issue is still a problem especially in the evenings. The neurologist did a nerve test and MRI and there were no problems noted on these tests. I also saw an ENT and had an eye exam and no problem there. I take 2,500 mg of Metformin a day. Will the B12 shots eventually help my balance issue? If so usally how long does it take before you see improvement in this area. Also I never liked taking such a high dosage of Metformin but my doctor wants to keep me on it because he feels its the best medicine for treating my Type 2 diabetes. Can I take another medicine that is just as effective as Metformin for treating diabetes but won’t result in B12 deficiency. What is the ideal B12 level if you are a diabetic?

  • acampbell

    Hi Vanessa,

    Not being a physician, I can only say that it’s possible that your balance issue is related to your low vitamin B12 level. A B12 deficiency can cause problems with balance. So, if this is the case for you, you should expect your balance to improve as your B12 levels come back up to normal. Normal blood levels of B12 range from about 200 to 900 picograms per milliliter. It will likely take at least a month to build up your B12 levels. There are other diabetes medicines that you could possibly take, although you’ll need to have that discussion with your doctor. Metformin is a very effective diabetes medicine, but there certainly are others available, too.

  • Lynn

    A month ago I was diagnosed with type 2 diabetes after informing my doc what my blood sugars were running and then a Hemoglobin A1C was done. They are not way high, I just monitor them regularly because I come from a Long line of diabetics on both sides of my family. Prior to this, I have been taking B-12 inj. every 4 weeks, iron, Multivitamin w/ iron, extra b-12 sublingual, recently extra vit D (50,000 iu weekly) because it was “practically nonexistent” I was told, though I never saw the results of that test. AFter 2 years of B-12 inj, iron, 3 months of Vit D plus otc vitamins/minerals, they are all STILL low. Now I’m reading the new medicine I’ve only been taking one month for diabetes can lower my B-12. That is worrisome. Gee, if only I knew why the others were so low and why I can’t get them up, I wouldn’t be so concerned.
    I’ve had a colonoscopy, upper endo., xray swallowing and other stuff. It is all concerns. Only have a period about every 4 months so that is not it either. I wish I had answers myself. Sometimes I wonder if I should come off of everything (also take inderol and lisinopril/hctz) and see where everything goes then start over again.

  • acampbell

    Hi Lynn,

    It seems puzzling why your blood levels of B12, iron, and vitamin D remain low. Have you been tested for pernicious anemia or atrophic gastritis (a chronic inflammation of the lining of the stomach)? Are you on the correct doses of B12 and iron? Perhaps your doctor would consider referring you to a specialist for further workup? I’d also suggest you speak with your physician about the use of metformin, knowing that it may lead to further lowering of vitamin B12 levels. There may be a better choice of medicine for you. Please let me know how you make out.

  • Lynn

    I know I have had a HUGE amount of blood tests. The only invasive type tests were a colonoscopy and a swallowing test done with a xray. I have also done several fecal occult tests. The xray test was for acid reflux and was told to take proton pump inhibitor , but the others were negative. I went back last week and was told to up my metformin to 3 daily based on my levels. I asked about the b-12 and she said he wouldn’t affect mine since I’m already taking two b-12 shots monthly. I am seeing an internest not a family doc nor general practitioner. So, other than endocrinologist for diabetes, who else would I see?

  • acampbell

    Hi Lynn,

    I checked with a colleague of mine. Again, remembering that by no means is this a diagnosis or treatment recommendation, he mentioned the following: There is a methylated form of B12 that may be beneficial for you, including the sublingual B12. Proton pump inhibitors may also deplete B12, in addition to the metformin, so a methylated B12 may be in order, in addition to the folinic form of folic acid. If you haven’t had one done already, a Schilling test is a test used to assess B12 absorption and can give the physician an idea of what may be decreasing the absorption. Regarding vitamin D, low levels of cholesterol can interfere with vitamin D metabolism, so find out what your cholesterol is. Your PCP would be able to order and interpret a Schilling test. Otherwise, perhaps a hematologist (a physician who specializes in blood disorders, such as anemia) could help.

  • thebigo

    There is no eveidence whatsoever that you can take too much B12

    B6 YES
    B12 NO.

    Sadly,ignorance within the medical profession especially diabetic specialists are unable to think ‘outside the box’

    when I mentioned the metformin – B12 link she said I didn’t have preconious anemia!!!!!

    B12 defficiency and it’s symptoms (of which over 100, most of which mimic MS, have been identified to date)occurs long before PA shows up in a blood test.

    In Japan the level at which serum B12 is considered low is 550 in the west it’s 200.

    If you are found to have a low serum B12 below 200 you will be given injections and when your serum B12 is re-tested again it can be 2000 or above with no ill effects.

    Dr Chandry of Peterlee near Newcastle has carried out some research after a patient who was confined to a wheel chair due to un diagnosed B12 deficiency and when he boosted her B12 levels to way above 200 she regained the ability to walk and most if not all her symptoms disappeared.

    The B12 available over the counter in the UK from health shops is the wrong type it has no effect as the kidneys remove it immediately from your bloodstream MB12 taken sublingualy is what is required to boost B12 levels not cynoB12

  • Syn Ferguson

    And people still don’t think we need health care reform…. I have Type 2 Diabetes, fibromyalgia and now anemia. With VA med coverage, I have yet to see an actual physician in over 12 years. I was never told about the B-12/Metformin connection and I note that I take a second med, Omerprasol, that also may interfere with B-12. The VA has had me in for iron infusions–weekly for 6 weeks to begin with, now monthly, and the nurse practitioner said the monthly infusions might be necessary for the rest of my life–but I don’t know what kind of anemia and/or what caused it. I take Tramadol for neuropathy in my feet and the aches of fibromyalgia. While the mental and physical improvement since the iron infusions began makes a significant improvement in my quality of life, monthly day-long trips to the hospital for life will also have a significant impact. I feel very short on information.

    I finally have an appointment with a hematologist, and want to make the most of it. Going in as a new patient with complex issues, what can I reasonably expect from the doctor, and what questions should I be asking? Thanks for your help. Syn

  • acampbell

    Hi Syn,
    Since the hematologist will likely be focused on your anemia, I’d suggest that you ask him specifically what type of anemia you have, and ask him if you should be checked for pernicious anemia, which can occur if B12 levels are too low. Be sure to mention the fact that you take two medications that may deplete B12 and ask if B12 supplementation or injections might be necessary. Ask about your level of folic acid, as well.

  • dollface

    i have a folic acid , vitamin d and vit b12 deficiency. had all sorts of blood tests and all come back normal waiting for gastric investigations but haven’t been told what these investigations are for can any1 enlighten me?

  • acampbell

    Hi dollface,

    It’s possible that your physician wants to check for an inflammation of your stomach, called atrophic gastritis, or perhaps a malabsorption disorder, such as celiac disease. These conditions can prevent the absorption of vitamins, leading to deficiencies. I’d suggest, though, that you ask your physician what tests are being ordered and for what purpose.

  • Peter Marsh

    I have been diagnosed with Vitamin B12 Anemia and yes i take 2grams of metformin a day, my question is if i stop taking the metformin with the Vitamin B12 anemia be reduced in any way and if so what time frame are we talking about. Thanks

  • acampbell

    Hi Peter,

    Vitamin B12-induced anemia can be reversed with proper treatment. However, it’s hard to say if stopping the metformin would reduce or reverse your anemia, since a B12 deficiency can result from other causes. You would need to have your vitamin B12 levels checked, probably for at least a few months, if not longer.

  • alicia

    Hi, after reading just a few comments along with reading the information above, it explains how i feel most times, a thousand thanks to you guys, God bless!

  • kctt1152

    I’m type 2, 55 years old, in good shape (work out four times a week) and I’ve been on Metformin for about 4 years. Just had a dr. test and tell me I have a b12 deficiency. He recommended a otc supplement in the 1000mcg range. I’ve read most of your blog ( the way). I get the impression oral b12 really isn’t effective. Is that your take? I hate shots…anyother otc alternatives? Thanks again for doing this blog!)

  • Richard Rasmussen

    I am a type II diabetic for which I take, metformin, actos, and januvia; I have sleep apnea and use a CPAP machinge at night, my high blood pressure is controlled by fosnopril, chronic sinus controlled by mucinex D, cholesterol controlled by gemfibrozil and welchol, enlarged prostrate problems quasi-controlled by sanctura and flomax, acid reflux controlled by prilosec OTC,chronic fatigue and/or depression????being treated with cymbalta, vivactil and adderall plus supplements, fiber laxative capsules, flaxseed oil tablets, multi-vitamin,and vitamin D tablet (400mg.)

    I am a 62 year old caucasin male, 5ft. 6in. with weight of 165. I have been receiving treatment for all of the above for about 10 years. I have had one minor stroke. I had complete recovery except for some loss of feeling on my left side.
    I have complained about feeling tired, fatigued all of the time for 10 or more years. In recent months, my family Dr. stated I needed V-B12 shots for anemia. I am an attorney but I am so tired some days I go back to bed after food and pills.
    I have not been able to practice law for over 3 years now. I am quite frustrated and seem to be getting worse. I would appreciate your observations and comment. Thank you. R.Rasmussen

  • acampbell

    Hi kctt1 152,

    Glad you like the blog! Actually, there’s evidence that oral B12 supplementation can be just as effective as injections, so that’s good news! Usual doses to correct a deficiency are 1,000–2,000 micrograms daily for 1–2 weeks. Check with your doctor about what dose is best for you. Make sure your levels are checked periodically after that, too, to ensure that your deficiency is corrected.

  • acampbell

    Hi Richard,

    You’ve certainly been through a lot! And there could be a number of factors causing your fatigue. Since I’m not a doctor, I can’t really advise you, but what I would suggest is asking your doctor or even a pharmacist to take a look at all of the medicines that you’re taking. It’s possible that some are interacting with each other. Perhaps it’s possible to consolidate some of them. You didn’t mention how your diabetes is doing — are your blood sugars running on the high side? That can lead to fatigue. Also, ask your doctor to have your vitamin B12 level checked as that may be low due to metformin.

  • jobin jose

    Is it possible to give metformin for a dibetic patient who is having vitamin B12 deficiency

  • anonymous

    There are many ways to treat B12 levels. There are injections, over the counter pills and a nasal spray you can take weekly at home.

  • tang

    I have been taking a multivitamin along with vitamin c and vitamin b. Lately I have noticed a change in my weight increasing. I exericise on a regular basis sometimes 2 hours a day and my meals are proportioned. I do not eat junk food and I only drink water. Can taking the vitamins cause the weight gain.

  • acampbell

    Hi tang,

    No, vitamins wouldn’t have an effect on your weight. Think about other possible factors that could be contributing to your weight gain: amounts of food, unconscious eating, fluid retention, hormone imbalances, etc. Keeping a detailed food and activity record for a week can be helpful, and you might consider meeting with a dietitian if your weight gain continues.

  • rachel

    i have type on diabetes and i was woundering if i get a shot of vitamin b 12 will it effect my blood sugar?

  • acampbell

    Hi Rachel,

    No, a B12 shot should have no effect on your blood glucose.

  • Jlamphear

    I have a question. I have never been diagnosed with anything, but have always had a lower iron count (as in could not give blood.) I also am overweight. I have done some reading, and would like to know if it is safe to take a 2500mcg sublingual vitamin b12, and take a 100 mg b6 vitamin at the same time. I am also on adderol. Adderol is prescribed, and I take that for add, and it doesnot help me stay awake during the day?


  • acampbell

    Hi Jlamphear,

    I’m assuming that you don’t have diabetes, as you mentioned you’ve not been diagnosed with anything. B12 is fairly safe to take, although I’m wondering why you are taking it? Do you think you’re not getting enough B12 in your diet? Also, 100 mg of B6 is likely more than you need, unless you’ve been diagnosed as being deficient, for example. Too much B6 over a long period of time can put you at risk for a type of neuropathy, or nerve damage. Taking 100 mg per day is likely to be safe, but there may not be a need for that much (the RDA is only 1.3 to 1.7 mg per day for adults). I am not that familiar with Adderall, but if you don’t think it’s working for you as it should, talk to your pharmacist or doctor — they should be able to guide you as to the right dosage.

  • Donna

    Could being low on vitimin B-12 make me not be able to walk. I am okay now but not sure as to why it came and went. One day I could not walk and 2-3 days later I could walk again very slowly. Then I am back to normal.

  • acampbell

    Hi Donna,

    A B12 deficiency could cause nerve damage which theoretically could lead to an inability to walk. Please call your doctor to let him or her know what happened as there could be many reasons for why you were unable to walk.

  • nrezinas

    I have been diagnosed with Type 2 Diabetes since Nov 2006. I was taking Metformin (1000mg daily), along with Avandia (4mg). In March 2010, the doctor increased my Metformin dosage to 2000mg daily. In early July 2010, I began experiencing unexplained dizziness when I moved my eyes. Blood tests were done, and everything came back “normal.” MRI was done, which was also normal.

    Dr. called and said that while my B12 was in the “normal” range, it was on the low end (290). I was started on B-12 injections, and after getting an injection every 2 weeks for 6 weeks, my symptoms are now gone. After doing some research on B-12 deficiency, I saw that Metformin can cause deficiency. I mentioned it to my doctor’s office, and they said that they have not heard of the link.

    I’m glad to know that I am not the only person with this problem. Doctors should know about this link!!

  • Jem

    I have PCOS and I have started taking metformin about one week ago. I was asleep and in my sleep I can feel my head getting extremely light, almost like going into a very very deep sleep. I have a slight case of anemia. What I want to know is could metformin cause me to get light headed, tingling in legs and other symptoms? I occassionaly take a dose of trihemic to help build my blood. Should I get vitamin B injections on a regular basis?. I have done numerous blood tests and they can find nothing else to indicate why I am getting these problems. Please Help.

  • acampbell

    Hi Jem,

    The most common side effects of metformin are nausea, stomach upset and diarrhea. These usually go away after a short time. However, dizziness, lightheadedness, and weakness are other possible side effects, too. To be on the safe side, you should give your doctor a call and let him know about your symptoms. You could also get your vitamin B12 level checked, too, and discuss B12 supplementation, since metformin could possibly lead to a deficiency.

  • Sheila

    I have been diabetic since I was 11yrs old I am now 48. I have always been insuin dependent. Blood tests prove that I am well controlled but last week having had my 6 monthly blood tests ready for diabetic clinic my GP has informed me that I need to take Cyanocobalamin tablets 50mcg tablets one twice a day. I asked my GP what he hought had suddenly caused this vitamin B12 defiency, he asked if I was a vegetarian to which I replied no. He then said perhaps your insulin has caused it I have been on Novorapid 3 times a day and Glargene before bed for 15 years. He then said talk to the diabectic nurse when you see her next week in clinic. He said that my liver/kidney function tests were excellent as were my diabetic tests, my cholestrol test was very good. I also take simvistatin tablets for my cholestrol so why have I suddenly got this defiency.

  • acampbell

    Hi Sheila,

    There are several reasons why someone might develop a vitamin B12 deficiency: inadequate intake of foods that contain B12; pernicioius anemia, an autoimmune condition that prevents you from absorbing B12; insufficient stomach acid; stomach surgery; and conditions that cause malabsorption, such as celiac disease, Crohn disease, or even having a parasite. B12 deficiency can lead to nerve damage if it’s not corrected. I’m not aware that taking insulin or simvastatin can lead to a B12 deficiency. At any rate, it’s important to take B12 supplements as directed by your doctor to correct your deficiency, and then follow up and have your B12 level checked again.

  • Aditi

    My husband has been diagnosed as a type II diabetes at the age of 25. He is 34 now and he has been taking Glimepiride and metformine combination tablets for last 6/7 years. He also takes diabetic multivitamin pack. He takes fibator for lipids.
    My question is can he take Vitamin B12 supplements? I recently learned metformin decreases B12 absorption. Plus, he consumes very less of meat, just some white chicken and very less of dairy.
    How much vitamin B12 should he be taking?


  • Georgina

    I have been on metformin for well over 10 years, I am 41, I was prescribed it for PCOS. In the last year or so I have been having so many different symptoms ranging from feeling sick, being constantly bloated, diarrhoea, constipation, swelling in my legs, pains in legs and numbness, not being able to breathe properly. I stopped taking metformin 3 days ago and started taking multi vitamins with iron, all of my symptons have now gone. I can walk without pain, my leg swelling has gone, I am not bloated and my bowel habits have returned to normal and I can breathe. I can only conclude that this was due to metformin and my body was depleted of B12. I’m not saying I have cured myself but I certainly feel so much better than I have done in the last year.

  • acampbell

    Hi Aditi,

    Check your husband’s diabetes multivitamin for how much vitamin B12 it contains. It should have at least 2.4 micrograms. Also, even though your husband doesn’t eat much meat, B12 is found in trout, salmon, tuna, yogurt, and fortified cereals, so he may be getting B12 from food sources. If you still think he’s not getting enough B12, you might have him ask his doctor to have his B12 and folic acid levels checked. B12 supplements are likely not harmful, but before he starts taking additional B12, it might be a good idea to first find out if he’s deficient. “Normal” blood levels of B12 range from 200–900 picograms per milliliter.

  • IVAN

    I am a type 2 diabetic. I started taking metformin 500 mg twice a day after meals at 6:30 am and at 5:00 pm. I started to feel sick every day.So my doctor said I should take both tablets after dinner. This seems to make me feel better. I also noticed I had no energy before. Someone said about my vitamin b-12 may be depleteing. I bow take a 100mg of vitamin B-12 supplement and I have my energy back. Is ther anything else I should do?

  • acampbell

    Hi IVAN,

    I just wanted to clarify: Are you taking 100 milligrams or 100 micrograms? 100 milligrams is a pretty large dose of B12 and may be much more than you need. You can also ask your doctor to check your blood B12 level to find out if you’re deficient. As far as energy goes, first, check your blood glucose and try to keep your levels as close to your target range as possible. High blood glucose can make you feel sluggish and fatigued. Second, eat a variety of foods, including carbohydrate foods. But go for healthy carbohydrates, like whole grain breads and cereals, fresh fruits, and nonfat or low fat milk and yogurt. Sugary carbohydrates can give you a quick boost but then later leave you feeling tired. And third, try to do some physical activity every day. The more active you are, the more energy you’ll have!

  • jim snell

    re metformin:

    Thamks for sharing about what some of the properties
    are. Another side effect of the drug is that when the drug of a standard 500 mg pill is up to strength in blood stream, my experience is that the liver is cut off from releasing glucose to blood stream. I se this at night and in fact that dawn effect gets blocked for time drug up to strength in Blood stream.

    With two 500 mg pills – one at 10:00 pm ans one at 12:00 am I see no glucose added between 1:00 am through 5:30 am. This is reliable and repeatable.

    no more 238-265 blood sugar mornings.

    i note salk institute comments:

    Scientists discovered a genetic “fasting switch,” called CRTC2, that flips on glucose production in the liver – the same switch that remains permanently on in patients with Type II diabetes. A collaborative study among Salk researchers revealed that a common diabetes drug (Metformin) works to inactivate CRTC2 and shut down glucose production. Having identified a molecular target for this drug, new, more active drugs will be easier to develop.

    In healthy people, a “fasting switch” only flips on glucose production when blood glucose levels run low during fasting. “The existence of a second cellular signaling cascade—like an alternate route from A to B—that can modulate glucose production, presents the potential to identify new classes of drugs that might help to lower blood sugar by disrupting this alternative pathway,” says Montminy.

    Public release date: 6-Mar-2008

  • acampbell

    Thanks for sharing the study, Jim!

  • James


    At 65, I have had Diabetes type 2 for 20 years. I take several medications including Metformin 2X850 daily. I have been taking insulin – 21 units of Lantus Solostar nightly for some years (makes me put on weight).

    Because of increased memory loss I stopped taking my Lipitor Satins some weeks ago. Now four days ago, due to recent reports of the advantages of B12, B6, and Folic acid, I began to take 500 mcg of Vitamin B 12 at night.

    For the next two mornings I awoke shaking and sweating, and sure enough, my blood sugar levels were dangerously low (50 – 60). yesterday I took the B 12 in the daytime and by evening even after eating and some alcohol my blood sugar was normal (140).

    Last night I didn’t take any insulin at all. This morning my blood sugar was again normal (141). I feel great and I will continue this B12 and no insulin for some days – carefully checking my blood sugar – but even now I believe this is going to mean no more insulin for me.

    Why not try it too?

  • acampbell

    Hi James,

    While I can understand how encouraged you are with your lower glucose readings, it’s generally not a good idea to completely stop a medicine without first discussing it with your doctor. He or she may recommend that you lower the dose rather than stop it completely. Also, the use of B vitamins isn’t a proven method for treating diabetes. Have you made any changes to your food intake or physical activity level that might be affecting your blood glucose? At the very least, as you mentioned, keep checking your glucose at different times of the day and then if you feel that you truly don’t need your insulin, give your doctor a call to discuss further.

  • Kim

    “Have had diabetes type ii for 5 years, have been on multiple medications, now on 1000 Metform, Actos and Insulin in the evening. Just found out I have a vitamin D deficiency, so am to start takingt 4000 units for a month then 2000 forever. Will it hurt to add the bComplex vitamins? Will thse help the joint pain, fatigue and depression? Can these vitamins help stop the diabetes or make it in better control?

  • acampbell

    Hi Kim,

    It probably wouldn’t hurt to take B Complex vitamins unless you take too high a dose. They won’t stop your diabetes or likely help to improve your control, though. And your joint pain, fatigue, and depression are probably due to other issues. I’d suggest that you discuss your symptoms with your doctor, and consider taking a vitamin B12 supplement rather than a B Complex supplement.

  • Danielle

    I have been on metformin for 4 years. In the last year I have lost two apparently healthy babies, one at 14 weeks and one at 18 weeks. So far, the doctors think it’s “unexplained” even after repeat pregnancy loss testing. I just got my records and my RDW on my CBC taken at 10 weeks pregnant had a high flag on it and when I researched what that could mean, vit B12 deficiency came up. When I looked up what causes vit B12 defiency, metformin came up as a possible cause. Have you ever heard that a B12 deficiency could cause a developing baby’s heart to stop? I am desperate for some answers. I will see a perinatal specialist this week for a consult and am looking for any ideas to bring up to him.
    Thank you for trying to help me.

  • Danielle

    I forgot to add that I am taking metformin for PCOS though my fasting numbers do show pre-diabetic.

  • acampbell

    Hi Danielle,

    I have not heard that a B12 deficiency could affect a baby’s heart. However, B12 deficiency during pregnancy could affect the baby’s nervous system, leading to neural tube defects. But, this is an excellent question to ask the perinatal specialist and I hope you get the answers that you need!

  • Steve Dauzat

    Can you take B-12 with Novolin Insulin

  • acampbell

    Hi Steve,

    Yes, you can take B-12 with any type of insulin.

  • James

    Hi Doctor Campbell and readers, I have not returned to your blog earlier because I naturally wanted to see the long-term effects that taking Vitamin B12 would have on my diabetes. You are right in that my stopping the Lantus insulin completely did not work, so after a bit of trial-and-error, I reduced it from 24 units to 10 – 14 units. I did stop my Metformin for some days but have restarted them.

    The result to date is that a vitamin B12 deficiency attributed to my diabetes, proven by the fact that by taking 500 mg of Vitamin B12 twice daily has reduced my dependency on insulin injections by about 50%. This has all been very encouraging and because insulin causes weight gain, taking less insulin means I also eat less.

    Clearly – whatever the cause – a vitamin B12 deficiency mimics diabetes by raising the blood-sugar levels, so I can recommend that anyone with diabetes tries Vitamin B 12. Just be careful, because if it works for you, you might start getting very low blood-sugar levels until you can adjust your medication to work alongside the vitamin B12.

    Best regards to all!


  • michael





  • acampbell

    Hi Michael,

    First, congratulations on all of your hard work! It’s not easy to make lifestyle changes. Your meal plan sounds pretty healthy, although it does seem a little too low in carbohydrate, especially since you’re doing a lot of running. Remember that your body uses carbohydrate for energy. Also, without knowing how much protein you’re eating, it’s hard to say if you’re eating too much. Second, while it’s sometimes hard to have to take medicine, you might try thinking of metformin as something that is helping your body use its own insulin better. In many cases, healthy eating and exercise isn’t enough to control blood glucose. Most people with Type 2 diabetes need medicine, so medicine isn’t a “bad” thing. And metformin is a very safe drug. What’s most important is that you are able to keep your blood glucose and A1C levels in a safe range to lower your risk of complications. There’s no magic pill or cure for diabetes at this time. My advice is to add a little more carbohydrate back to your diet, continue with your exercise, and continue with your metformin. I’d also recommend that you meet with a diabetes educator at some point, too, to get any of your other questions answered.

  • Kim Huff

    I am a 47 year old obese female. I just found out that I am insulin resistant so my doctor put me on Metformin. Since then I have been incredibly tired and cannot even make it through a day without taking a 3 to 4 hour nap. Before I started taking the Metformin, I was taking B6 and Magnesium to help with some issues I was experiencing during my menstrual cycle. I read somewhere that I am not supposed to take vitamins with the Metformin so I have not been taking my vitamins. Does anyone know if this is true? Can I continue to take my Metformin at the same time as I take my Magnesium Citramate, Pyridoxal 5′ Phosphate (B6) and my Alpha Base without Iron Multivitamin?

    Thank you for your help.

    Kim Huff
    Indianapolis, IN

  • acampbell

    Hi Kim,

    I am not aware that one shouldn’t take vitamins with metformin. To my knowledge, you can continue to take your dietary supplements. You may want to double check with your pharmacist, however. As far as your fatigue goes, there could be several causes. How is your blood glucose levels? If they are high, that can make you feel very tired. It sounds like you’ve just started on metformin, but people who have been on metformin for a while may become deficient in vitamin B12. My suggestion is to let your doctor know about how tired you are (and let him or her know how your blood glucose levels have been running) so that he can pinpoint what the cause might be. I’d also suggest that you let him know about the dietary supplements that you are taking as well, including the doses (to make sure you’re not taking too much).

  • Konrad

    Hi a campbell

    Thank you for tis subject. I have been taken metformin for more than four weeks now. ( 500 mg a day ). With vitamin B complex tablets.
    I was very happy at the beginning because I didn’t fell any of the side effects reported to be associated with metformin.
    But recently I’m getting a terrible headache that cannot be
    bearable. And two days after stop talking metformin and vit B complex together. Now I’m feeling better .

    Do you have any idea of which will be the cause of the headache. Metformin or vita B complex.
    I will try to take one by one to check which one of them is the cause.
    Does oral supplement of vit B complex or B 12 will be enough to overcome the B12 deficiency or injection is best
    Because I have read some where even oral supplements will be not efficient due to Decreased absorption rate induced by metformin .

  • acampbell

    Hi Konrad,

    Headaches are a possible, but uncommon, side effect of taking metformin. Of course, other things can cause headaches, too. It’s generally not a good idea to simply stop taking your diabetes medicine unless advised by your doctor. I’d suggest giving your doctor a call to discuss why you’re getting headaches and how to best treat them. Oral vitamin B12 can work well to correct a deficiency, although older adults, for example, can’t always absorb B12 in their intestines and may need injections. Your doctor can check your vitamin B12 status by doing a blood test and if you’re deficient, recommend the appropriate dose. Some doctors are prescribing a once-a-year 1,000 microgram injection of vitamin B12 for their patients on metformin, so it’s something you might talk about with your own doctor.

  • Susan

    My mom has diabetes and takes B12 shots. Her dr told her she had to wait 30 days between injections, and have turned her away if she came in for it too early. She gets her RA iv every 28 days. I try to combine them and want to know if there is a rule on the time frame for the B12 injections. In all my readings on the web so far, I haven’t seen anything that mentions that. I’ve seen where people take them every day, every week, every 2 weeks, etc. Thank you!

  • acampbell

    Hi Susan,

    My understanding is that a B12 deficiency can be corrected by getting injections every day for a week or so. Once the person is no longer deficient, injections are given monthly (there’s no need to give them on a daily basis). I don’t know, however, if there is any harm in giving a monthly injection every 28 days vs. every 30 days. Perhaps the strict time frame has to do with insurance coverage? You might ask your local pharmacist this question as they would likely know.

  • Jim Koch

    I am a type 2 diabetes and am on Lantus Solostar 40 units in the AM and 40 at night I also take Humalog at meals and Metformin at 1000 mg at breakfast.
    I have read most of the comments and responses above but do not see any that cover my problem My question to you is would vitamin B-12 help reduce cramping in the upper and lower legs. I have tried Cinnamon for about two weeks now,and have noticed a little less tingling in my feet and hands. However the cramps are still with me.The doc put me on Flexril for three weeks and I have been taking Bio-CMP tablets for a couple of months and neither seem to be a fix for this problem. Any suggestions you may have will be appreciated.

  • acampbell

    Hi Jim,

    I’m not a doctor, but my understanding is that leg cramps can be caused by a number of factors, including dehydration, perpipheral arterial disease, certain medicines, and low levels of calcium, potassium, or magnesium. My suggestion is to talk with your doctor about what’s causing the cramps in the first place. Vitamin B12 may possibly help, but you should know why they’re occurring in the first place so that they can be appropriately treated.

  • Mike

    Hi acampbell.This could be a bit long. I am 60. Have avoided medical care due to lack of Ins. all my life. 7 months ago started falling down due to leg weakness. Finally I could not get back up without help. Went to a clinic/sugar level 230/ put on Metformin 1000mg. morn. and again evening/ refered to Neurologist/emg showed severe Neuropathy/ prescibed Neurotin and B12 weekly injections/ had an allergic reaction and quit the Neurontin/ 1 week later had another allergic reaction( back on the prednosone)/ quit the b12. Here it gets awful. In the past 6 months have suffered severe muscle atrophy over practically my whole body to the point I’ve lost 30 pounds+. Don’t know for sure as I can’t stand on a scale. I can barely rise with the help of a walker. Saw my family Doc. whose only suggestion was to try the Neurontin again at a low dose and of course-Reaction again! Now I’m gunshy about the b12 injections. I bought some subligual 1 mg methyl Cobalamin ( my pharmasist told me the oral is basically useless but sublingual will get at least 60% into your system) and have been taking 2 a day for a week. Nothing noticeable has happened but that could be due to all my pain(lower back is cronically horrible let alone the rest). Could this be b12 deficiancy? Thanks for any feedback as I’m a bit of a mess. Mike

  • acampbell

    Hi Mike,

    You’ve certainly been going through a lot. Are you able to see the neurologist again? Or go to another neurologist? There are other medicines besides Neurontin that can help treat the pain of neuropathy so it may be a matter of finding the right one for you. Other treatments for neuropathy pain include capsaicin cream, alpha lipoic acid (which is used in Germany to treat neuropathy), acupunture, and a procedure called transcutaneous electrical nerve stimulation (TENS). These aren’t necessarily “proven” treatments but they’ve helped some people. You might also ask your doctor about a referral to a physical therapist who can work with you to prevent further muscle atrophy and help you build up your strength again. As far as the B12 goes, since you’ve been taking it for a week without a reaction, that’s a good sign. You should ask your doctor to do a blood test to check your B12 levels. If you’re deficient, it will take longer than a week to restore it. I hope this helps somewhat. I do think you need to revisit the neurologist or at least find someone who is willing to work with you and try different treatments to improve your pain and your muscle weakness.

  • Mike

    Thanks for the response acampbell. My question really was could a low b12 cause alot of my damage. I’ve already been told by professionals that Diabetes could not cause so much damage so quickly. As far as drugs other than Neurotin(such as Cymbalta, Topamax and Lyrica)the problem is they use the same ingredients and I’d still have reactions. Physical Therapy isn’t going to help at this time as I’m still suffering new damage. Today it’s my right arm going dead in one area. This is why I’m so curious about b12. An affordable blood test is available on the 19th. Thanks again. Mike

  • Mike

    Sorry to be a pest, but I forgot something. I believe I saw somewhere that low b12 caused lower back pain. Mine is awful.I’ve had x-rays and a ct scan but nothing shows abnormal. Thanks for the tip on Alpha lipoic acid! This is off thread, but I think important. 6 months ago a nurse practitioner prescibed Ultram(tramadol) for pain. It’s supposed to be nonaddictive. NOT TRUE! I read on a blog about all these people going through horrible withdrawals from it. It was also discovered that it is an anti-depressant. I quit taking it 4 days ago and it sure has been awful. Next I guess I’m supposed to get very depressed. I’m adding this cause it’s been tough enough without lies about addiction. Mike

  • acampbell

    Hi Mike,

    It’s possible that a B12 deficiency could be responsible for some or a lot of your symptoms. Also, I too have read that low B12 could cause back pain (along with weakness, numbness, tingling and other neurological symptoms). So it’s a good thing that you’ll be getting this checked in a few days. Let’s hope that you’ll be feeling better soon. Let me know how things turn out.

  • Judy Scaccia

    I am reading the info on B-12 it states take1000 to 1200 Calcium this is not good for people who have kidney stones. All drugs affect one part of your body or another and I find it difficult to believe that no one lets you know this when you are diagnosed with such things as Diabetes, Kidney stones etc – DR. spends a total of 5 min with you – does not explain anything and you have to be smart enugg to research each and every drug you take. I also take High BP meds – many of which cause itching, coughing, tiredness, ear aches and mostly bla feeling. Anything that ends in ol is bad for coughing – itching and just recently I tried valsartan which promptly gave me a sevear ear ache which persists even when I stopped taking it. Sometimes I think we are living on borrowed time with any drugs we are given and I for one, believe in herbs and God’s healing power – if the diabetes drug I just started this week end presents alot of symptoms I and also pitching it in the garbage with alot of all the others that cause severe side effects from the get go – if you have kidney stones the dr does not tell you to not eat spinach, chocolate,strawberries, rasberries, calcium, Vit D, sugar, sweet potatoes, grapes, celery, green pepper and peanuts,alot of which cause gout too – you find out on your own by researching your delima and finding out – Oh – NOONE told me this – and they think I am crazy because I hate doctors. Did you know that Zocar or statins can destroy your brain – and cause bad dementia – our body needs choloresterol to function – our brain needs it to work right – deplete it from your body and you are a new alzheimers patient?? It eats muscle – and your heart is a muscle, and I have read that women should never take statins. Do the doctors tell you this??? Of course not. Drugs will kill you before any disease will – I have diabetes because I love to eat??? All the wrong stuff – they are forcing me to lose weight and I don’t care aif I do or not – but now I am forced to -high blood sugar can kill you too – you have to use common sense to heal yourself – your doctors won’t take the time to talk to you and explain anything – they are too busy worrying about the next patient they have to see behind you- and don’t like it if you ask questions. I have never found a DR yet that I trust except DR Philip Morrow in Louisville – for thyroid problems – he did a thorough exam and I mean thorough. He is precise and to the point and you can take his word to the bank about your health. He is my Hero to this day. So folks take control of your health issues, do the research and feel better – fast. Thanks

  • Alice

    How long does a vit B infusion take?

  • acampbell

    Hi Alice,

    If you’re referring to an injection of vitamin B12 (which is typically how B12 is given aside from taking it orally), the injection would take seconds. An IV infusion of B12 is not as commonly used, but could take anywhere from 15 minutes to a couple of hours, depending on how much is needed.

  • odeth

    I learned a lot from this blog especially about anemia, tingling of legs and thighs. lightheadedness and diarrhea. My physician told me that I’ve pernicious anemia and she orderedan Intrinsic Factor, after finding from my last blood test that my Vitamin B12 is less than 200 picogms/mm. She told me that the test Intrinsic Factor is the test for pernicious anemia. She hasn’t called me yet about the result. If this test is positive, she’ll give me Vitamin B12 injections. I don’t have an appointment with her until April 6. I hope and pray that this test is negative. I’ve diabetes2 and taking Metformin 500 mgms 2times a day ( one at breakfast and one at dinner with food ).I hope that the shots will take away all those side effects mentioned above.

  • Amanda Steger

    I have been on Metformin and Glucotrol for several years because of diabetes (2). About 2 yrs. ago I was diagnosed with severe pernicious anemia. I have been taking B-12 shots twice a week. I have been to several doctors and always show a list of my medications to which none have mentioned the Metformin.
    Should I bring their attention to the Metformin possibly being a problem with my B-12? Is there another medicine that could be used instead of Metmormin or maybe Glucotrol be increased in dosage, etc. ?

  • acampbell

    Hi Amanda,

    It certainly couldn’t hurt to mention the link between metformin and possible B12 deficiency. It may be that your doctors need a gentle reminder! You may not necessarily need to stop taking metformin, provided that your pernicious anemia and B12 levels are regulated. However, there are many other diabetes medicines that you can take, too. It’s definitely worth a discussion with your doctor.

  • susan

    ive been on metrofmin for over 10 years and and at present also on insulin, i am always tired dont sleep too well but not being diognosed with B12 dificancy so would taking a vit b complex help or should i take just B12.

  • acampbell

    Hi susan,

    In general, it’s always a good idea to find out the cause of your symptoms before you start to treat them. So, in your case, if you’re feeling tired and aren’t sleeping well and you can’t link these to obvious things (like going to bed too late, drinking coffee at night or stress), then it’s worth checking with your doctor first. It could be that your B12 levels are low, but your doctor should confirm that with a blood test, and then could advise you as to how much B12 to take. In the meantime, you could take a multivitamin that contains B12 or even take a B-complex supplement.

  • jim snell

    This article stiring up the dust and making folks panic is waste of time. Take B12 supplement and move on.

    For anybody with liver leak/dump; metformin is the most powerful drug out there. Anecdotal evidence from comments about retina business being cut back since introduction of metformin alomg with latest research sugest very powerfull reasons to take metformin correctly and on regular basis.

    Article from John Hopkins also speaks volumes:

    we do need any more mouse tests, I am going to register as lab mouse and submit my body and results on metformin that backs up these results to the hilt.

    My diabetes would require far more insulin added without metformin.

  • Audrey

    I just found this blog today by seeking information on, and I learned a lot. If appropriate, I’d like to mention that I also learned a lot from reading a book I ordered on Amazon: the second edition of Could It Be B12?: An Epidemic of Misdiagnoses, authors Sally M. Pacholok and Jeffrey J. Stuart, nurse and doctor respectively. The book isn’t about Metformin specifically, though, instead is very far ranging. I had no idea how devastating too-low B12 could be, thus how important it is to have our B12 levels tested. Doctors differ, as mine did not check B12 for almost 20 years. My new doctor, however, tested my first visit. The book discusses that problems may become permanent if B12 deficiency is not treated, so I think we must all become proactive in reading sources like this blog and the book so that we can urge our doctors to protect our best interests by testing for B12, or find another doctor. A problem the authors point out is that what many labs and doctors consider a normal range is in fact too low, my new doctor agreeing and wanting to bring my B12 up a whopping three times higher than my initial test! So I think we should all seek information on this subject, which seems akin to the vitamin D issue, when it, too, now must be higher than was at first thought to be adequate.

  • carnatic singer

    I have been diabetic for the past 3 years. I take metformin 500mg twice daily. I am a vocalist and I have started developing voice problems ever since I was diagonised with diabetes. I get tired easily and seem to be losing control over my voice. I got blood test done and my doctor said I don’t have any deficiency. ENT speacialist said there is absolutely no problem with my throat. Any clue on what might be causing the problem?

  • acampbell

    Hi carnatic singer,

    This really isn’t my area of expertise, but I did a quick search and came across this information on diabetes and vocal cord paralysis:

    Now, not being a doctor, I’m not saying this is what you have, but it’s interesting that there does seem to be a link between vocal cord disorders and diabetes — perhaps it’s a type of neuropathy. My suggestion is to share this information with your ENT specialist or ask your physician to refer you to a neurologist.

  • eswynn

    Hi, My wife was diagnosed with Pernicious Anaemia 20 odd years ago,She has been taking Glucophage 500mg for about 2years. In Sept. 2010 her injections of Vitiamin B12 were stopped, since then her health has declined, she has become lethargic & suffers bouts of memory loss. She went into a coma for 7 days & the Doctors are thinking she may have NASH (non alcoholic liver disease)could the metformin be cancelling out the B12 ?

  • acampbell

    Hi eswynn,

    I’m really not sure, but given her history of pernicious anemia and the fact that she had been given B12 shots but they were stopped, it’s certainly something that you should ask her doctor. Hopefully they’ve checked her B12 levels.

  • metforminsideeffects

    Good Post! Metformin may help in the beginning to assist your weight loss efforts.

  • Brandy Carter

    Thank you for the post. I recently asked my doctor to test me for B-12 Deficiency and anemia after reading several articles about Metformin and the link in B12 Deficiency. I have been exhausted now for over 4 years and did not know why. I was diagnosed with Diabetes (prediabetes any who) over 2 years ago but before that I had extreme signs of PCOS with no doctor willing to diagnose my issues as that. My hair is falling out, tired, slow memory, vertigo daily,extremely irritable, cannot digest food well, constipated etc, etc. This was after beginning Metformin again after being off for 2 months ( I moved and waited to find a new doctor). Prior to the new dosage I didn’t have the constipation before. After giving my doctor this info 4 months ago I was told to take a multivitamin, probiotics, and get more rest. LOL I did that even went on a diet and though I felt better (gluten free, then liquid diet/Medifast) I still could not digest, hair falling out etc. Two sisters are diabetic and on insulin and their issues are no where near the same as mine. I hope I can get more help with this as I have a score of issues that doctors don’t seem to care to address. If you get one diagnosis they chalk every single symptom you have to that issue. Tired? diabetes Tingling hands and feet? diabetes. My issue is that if I am on drugs that are controlling my insulin levels properly, why would I still be having the same symptoms as when it was not under control? The tired is from your sugar being high-my levels have been great for over 2 years now, even lost a smidge of weight. Hope everyone reads this article and get more help from their doctors to deal with the “pill miracles” they keep giving us.

  • Stu


    Great blog btw! Have read all the above and my Mum’s case is v.similar; she’s been on Metformin for about 18mths (850 mg three times daily) and in last four months has shown signs of memory loss, poor balance, confusion etc. She’s been on Vit B12 injections for about six mths but energy levels in between injections v.poor (injections now seem to wear off after a few days).

    Difference is that she is taking Gliclazide (80mg twice daily) for excess calcium production so not sure taking calcium as a supplement a good idea. She has a doc’s appointment on Tue next week so we’re just trying to get as much info to present to the doc as possible. Would you be able to comment on whether calcium supplement might work based on above please?

    Thanks a lot!

  • acampbell

    Hi Stu,

    Thanks! Glad you like the blog. Gliclazide is a sulfonylurea, a type of diabetes pill that stimulates the pancreas to release insulin. I’m not aware of it being used for calcium purposes, however, or how calcium ties into it. But your mother may benefit from a calcium supplement to possibly help lessen the B12 absorption. Adult women need 1200 milligrams of calcium daily. Also, your mother may benefit from switching to another method of getting her B12, either sublingually (under the tongue) or a high-potency oral supplement. Ask her doctor what he would recommend.

  • Jason R

    About 10/12 years on Metformin. Can’t remember

    Hi all,
    I’m 57 now. Final stage of LADA. I can’t remember if I noted my memory loss when I started on Glucophage. I’m very in tune to my Body so, I suspect I might have. I know I’ve acknowledged it for most of the time I was on it.
    In the years before switching to insulin, I would have spells in the shower where I couldn’t remember what phase I was in. It was some what horrifying. I thought I was getting dementia at 55 years old! Those spells mostly disappeared when I went off it. My Nurse/Dr. ho hummed my complaints. I sure feel like a victim. It’s not fun at all.
    I would suggest a civil suite. If I had to compare memory loss. Losing a leg would be a toss up. You just don’t know what you’ve lost until it’s gone and your memory is vital.

  • Donnie Doyle (Warren)

    Hi, A number of years ago, a friend told me that the pancreas used b vitimans to produce insulin. Is this factual? I am very interested in this because my husband is a diabetic. He takes B-12 & B-6 daily He has backed off taking some of it and his blood sugar is higher now than before. I thought that perhaps this has contributed to less insulin being produced. Thanks. dmd

  • acampbell

    Hi Donnie,

    A few of the B vitamins play an indirect role in insulin production, but it’s doubtful that your husband’s blood sugar was being kept in control by taking B6 and B12. At least, to my knowledge, B vitamins are not a major factor in insulin production.

  • mp

    I take Metformin and I have been having tingling in my face and the back of my head. Has anyone had these kinds of symptoms?

  • acampbell

    Hi mp,

    Did these symptoms appear when you started taking metformin? In any case, I suggest that you let your doctor know.

  • sonia


    i m taking B12 1200 mcg for making blood in in my body i read the benifits of B12 and bought it.i ate B12 1200mcg which is jaimsons named form canda .so my periods skipped and constipation too so i leave it now plz tell me that its all of this tablets or some thing else.B12 1200mcg is okay for any one and its safe or not . i m married and 37 years old no child yet. my huband has very low sperm counts so how can i pregnent so can he use also B12 1200mcg for infertility ..
    should i eat B12 or leave plz tell me .

  • sonia

    me and my husband has no medically proble at all instead of infertility

  • acampbell

    Hi sonia,

    Vitamin B12 is a pretty safe vitamin, so I don’t think it’s causing your constipation. The dose that you’re taking is usually what’s given when someone is deficient, and you probably don’t need to stay on this high of a dose. I do not think that vitamin B12 is related to infertility, so I’m not sure that it would help your husband. The best thing to do is talk to your doctor about any side effects and questions that you have, and whether you should keep taking B12.

  • cindy

    I am a type2 diabetic. diagnosed march 2011. am currently on 1000milligrams Metaformin (500×2 daily) My problem is massive hair loss. I have some balding on the top of my head and I can run my hand through my hair and come up with alot of hair. I heard the medication can cause hair loss because of B12 and folic acid deficencys. I currently take 1000mcg B12, and 400mcg daily. I dont know if that is enough as I am still shedding badly. What is a safe amount of those two vitimans for a person who is diabetic?

  • acampbell

    Hi cindy,

    Hair loss isn’t a common side effect of metformin, so I’d suggest that you talk to your doctor about possible causes and treatment. To answer your question about safe levels of B12 and folic acid, B12 is a very safe vitamin so the dose you’re taking is likely OK. For folic acid, you shouldn’t take more than 1000 micrograms each day (and don’t forget that you get folic acid, or folate, from food, too).

  • Marty

    I started taking Metformin for type II diabetes, around 1998 and immediately started having memory problems. Trouble thinking and confusion. I had been in the Air National Guard for over 25 years and was now the Supervisor and while doing a report I couldn’t spell ‘Guard’. I kept trying and trying finally I looked at other paperwork and got it. I have always been a good speller until I began the medicine. Over time I never saw any correction of my blood sugar readings, it was always the same for the most part so I quit it. Immmediately my memory improved until it was no longer a problem. Around 2003 my doctor said my diabetes was worse and that I needed to go back on the medicine. He switched brands I forget the first new one we tried but then we went to ACTOS, all the med’s affected my memory. The thing is I again quit taking the medications (about 4 years ago) but the memory loss and confusion is still there. I have come to believe that Alzehiemers is caused by Diabetics taking these medications. The real curious thing is that my blood sugar never changed or imnproved on any of these medications. Sorry this got so long…

  • Sharon

    I recently read about the B12 level in diabetic have been low.

    My blood sugar numbers have been going up in the a.m. So after testing MD increased me from 500 mg twice a day to 1,000 twice a day. My Md told me to increase it slowly which I did. After about a month on it the number started to increase even tho I wasn’t eating anymore food.

    I read about the B12 level and Metformin people having lower levels. So after checking with MD if I could take B12 started them. About 2 weeks after starting my Charlie Horse that I had once or twice a month disappeared. My morning blood sugar number came down. I’ve been on the B12 about a month and they are staying in the good range. I have an appointment with MD next month and will have the B12 level checked.

    Last year I had read about the Vit. D level being lower in Diabetic. So I had my MD check that and even tho my Bone Density was good I had low Vit D level. My MD put me on Daily Vit D tablets.

    Has anyone else found that when taking B12 that your blood sugar numbers came down?

    I tried the Cinnamon and that didn’t do a thing for the blood sugar readings.

  • acampbell

    Hi Marty,

    I’m not aware of metformin immediately having an effect on memory, but it’s certainly possible that longer-term users of metformin could have issues or become confused due to impaired vitamin B12 absorption. Interestingly, metformin has been linked with both an increased risk and decreased risk for Alzheimer.

  • Maria

    Okay, I might have missed it but, how much is too much of vitamin B-12.?

    I do take the tablet form Glip/met at 500mtab (whatever that means) 2x a day.

    I went to the store (Wal-mart)and bought a bottle of Sublingual High potency B-12 at 2500 mcg’s. If that is too high can I break the tab into halves or fourths to tone it down.

  • acampbell

    Hi Maria,

    Luckily, vitamin B12 is pretty much nontoxic, even in high doses. Two clinical trials looked at somewhat high doses of B12: 400 mcgs given over 40 months, and 1000 mcgs given over 5 years. No adverse effects were noted. However, 2500 mcgs is pretty high, especially since adult women only need 2.4 mcgs, based on the RDA for B12. So, my suggestion would be to cut your tablets in half, just to be on the safe side. You likely don’t need that high a dose, anyway.

  • Maria

    Thanks Amy.


  • Sharoon Gerber

    My husband has been taking Metformin for type 2
    diabetes (2000)mg a day for years. Now he is very low in B-12. Should he continue with Metformin ? What is your advice.

    Thank you,
    Sharon Gerber

  • acampbell

    Hi Sharon,

    Metformin is a very effective and safe diabetes medicine. If the metformin is working for your husband (meaning, it’s helping to manage his blood glucose and A1C levels), then he can certainly continue taking it. He should, however, talk to his doctor about correcting his B12 deficiency (such as through an injection), and then start taking a vitamin B12 supplement.

  • ruby

    i was just diagnosed with very low vitiam b levels with numbness tingling shooting pains brain fog my doctor told me to take 2000 mcg of b12 why not the injections my numbers were 73

  • acampbell

    Hi ruby,

    Vitamin B12 deficiency can be treated with injections or pills or with a nasal spray. Pills are easy to take and are less expensive than injections or sprays, which is likely why your doctor prescribed them. And 2000 mcg is a standard dose to take. Make sure you follow up with your doctor to be sure that your B12 levels have returned back to normal (this may take a few weeks or months). Also, find out if you will need to take a maintenance dose of B12 to prevent it from reoccurring.

  • mani

    Hi Amy,
    Thank you for the valuable information.My husband has been on metformin for 10 years now. He has dangerously low levels of B12 the reading being 76. His doc has put him on injections for 10 days and told to get endoscopy and colonoscopy done. Why is that? Feeling very anxious. I mentioned about the metformin and B12 connection but our doc is also unaware of it.

  • acampbell

    Hi mani,

    Metformin is a great medicine, but unfortunately, one of its side effects is to hinder the absorption of vitamin B12, leading to a possible deficiency. This is actually fairly well documented, so it’s too bad that your husband’s doctor isn’t aware of it. However, his doctor is being on the safe side, too, by ordering the other tests to rule out any other possible conditions that could lead to low B12 levels, so that’s a good thing!

  • Anne

    I had my b12 levels tested and the result
    s came back with a rectangle half filled
    with stars but no numbers. My GP said it
    was in the normal range. Is this the
    correct test? I am on Medformin 1000
    twice a day and januvia. I have tingling
    in my hands.

  • acampbell

    Hi Anne,

    I’m really not sure what the rectangle and stars mean, but there should be an actual number. Ask your doctor again, or if he or she isn’t sure, perhaps you can contact the lab that ran the results. A “normal” B12 level is more than 200–835 picograms per milliliter (pg/ml) or 148–616 picomoles per liter (pmol/l), although this may vary from lab to lab.

  • jim snell


    I must offer that this sweating of the b12 deficiency while of interest pales in the signifigance of value of metformin against liver leakage.

    Yes check ones B12 levels but one can rot out on the diabetes issues. We need to temper the radar sensitivity level versus the issue.

    Job 1 should be stop the rot. Joob 4.5 should be check vitamins, levels etc and be sure your supplements are sufficient.

  • LarryE

    Hi. I’ve been reading all these comments and decided I might as well ask also. I’m considered borderline diabetic and am on Metformin 500mg once daily. My primary care physician told me that if my test came out under 113 that I do not need to take the Metformin. My tests have been fluctuating between 114 and 130. Just today I started taking a multi-vitamin which contains 5mg of B6 and 12mcg of B12. It also contains several other ingredients. Are those quantities of the B6 and B12 safe for me to be taking?

    Thank you in advance for any advice/suggestions/help.

  • acampbell

    Hi LarryE,

    You might also ask your physician to check your A1C level, if it hasn’t been done so already, just to give you a bigger picture of your blood glucose control. But, regarding your vitamin question: The amounts of both B6 and B12 in your multivitamin are fine. The RDA for B6 for men is 1.7 mg, but the upper level is 100 mg per day, so you’re well within the safety range. The RDA for B12 is 2.4 mcg for men, and there is no established upper level, as this vitamin has an extremely low risk of toxicity.

  • LarryE

    Thank you @acampbell for your quick answer to my question, I really appreciate it. I’ll contact my physician to check the A1C level. If they did do it, I was never told about the results.

  • miranda

    I take Metformin for PCOS, when i first took the pill it made me sick. for the first two days I could not eat and every time I moved I was dizzy and did not want to move. I ended up staying in bed for the two days. I had to take one 850mg twice a day, after the first two days I started cutting them in half and taking just a half one for one week, and going up half a pill every week. I still have no energy, I stay up half the night, but want to sleep all day. I am going to try taking b12 to help.

  • acampbell

    Hi miranda,

    Taking B12 may certainly help, but you may want to speak with your physician about your symptoms, as they could be due to other factors. He or she can also check your B12 level, too.

  • savira

    i am getting married soon and i would like to have a 36 and i am on insulin.what can i do to strenghten my womb and have a safe pregnancy? what vitamins can i take?

  • acampbell

    Hi savira,

    Best wishes for your upcoming wedding! One of the most important things you can do to ensure a successful pregnancy is to get and keep your blood glucose levels under good control before you get pregnant. This also means keeping your A1C under 7% and as close to “normal” as possible. Other important steps are to reach a healthy body weight (if you’re not already there), follow a healthy, balanced eating plan, and get regular physical activity. It’s recommended that you meet with your physician before you become pregnant to discuss your glucose and A1C goals, address any complications that you may have (like eye disease or high blood pressure), and review your medications (some are not safe for pregnancy. It’s a good idea to meet with a dietitian before you become pregnant, too, to review your eating plan and make sure that you’re getting all the nutrients that you need. Diabetes control needs to be very “tight” during pregnancy to limit the chances of problems, so controlling your carbohydrate intake and your weight will be important. A dietitian can also advise you as to which supplements you may need, in addition to a prenatal vitamin. Some other dietary supplements may not be safe during pregnancy, so always tell your health-care team about any medicines and dietary supplements that you’re taking.

  • Gina

    I can tell you that I take B-12 injections 3 times a week and it helps me tremendously with the drowsiness, the foul urine smell is completely gone away and the leg cramps subside. B-12 also caused my high triglycerides to drop 500 points.

    Works for me.

  • Robert

    I have been taking Metformin for a number of years to help control my blood sugar. Recently I had to have cervical vertebrae fusion to removed pressure on my spinal cord which had resulted in going from normal activities to a wheel chair in about a four to six week time period. The surgery appears to have been successful,it has been about 12 plus weeks since the surgery. I am able to walk with the help of a cane, but have not been able to resume normal activities due to balance issues and numbness in my right leg. Could there be an additional link to B12 deficiency due to the continued used oa about 1000 mg of Metformin per day? Does anyone out ther have any experience with this type of situation. I would really like to be able to resume normal activities, but it is just not happening. Perhaps I am being too ambitious with my anticipation.

  • acampbell

    Hi Robert,

    I’d suggest that you ask your physician to check your blood level of vitamin B12, as it’s possible you could have too low a level or even a deficiency.

  • KatieF

    Is it safe to discontinue Metformin without “tapering” the dosage? I’ve been taking 500mg 2 times daily for several months, but I believe my chest pains are related to Metformin and want to discontinue it to see if the pains stop. Thank you, K.F.

  • acampbell

    Hi KatieF,

    If you’re having chest pains, you really should call your doctor right away. That’s not something that you want to wait on. Also, I wouldn’t recommend stopping your metformin without first discussing it with your doctor.

  • Racheal

    I am diabetic and I was wondering if I can take b12 2500mcg or will it affect my medication?

  • acampbell

    Hi Racheal,

    If the medication you’re referring to is metformin, then likely, no. It’s always a good idea to let your physician know about any supplements that you’re taking, however.

  • Mckenzie

    I have been suffering through PCOS and its at its early stages. the doctor asked me to take metformin for about 6 months twice a day, a total dose of 500grams a day. i just needed to consult whether taking this medication may not lead me to a deficiency of vitamin B12. or any other side effect i would be facing after such a long term medication. should i be taking vit. B12 supplement too along with it?

  • Mckenzie

    does metformin cause vitamin B12 deficiency

  • acampbell

    Hi Mckenzie,

    Yes, there is a link between taking metformin long-term and vitamin B12 deficiency. However, this does not mean that you shouldn’t take metformin, as this is an effective medicine for both PCOS and Type 2 diabetes. But it does mean that you should talk with your physician about the risk for a B12 deficiency and whether or not he or she would advise you to take a supplement at this time and how often your B12 levels should be checked.

  • Ingrid

    Thank you all.. I have just starting taking bcomplex..and am not gonna stop.. I finally have some energy.. i have Diabetes and I take metformin.. and boy all that everyone has been saying here i true.. Energy levels are up.. I can exercise and not feel like i need to rest for the rest of the day.. and i am feeling better all round.. Thanks …

  • Jill

    I have taken 1000mg/day of Metformin for several years for type 2 diabetes. I have also begun a vegan way of eating in the last couple of months. My blood sugar levels are tightly controlled now. I just now became aware of this B12 issue. Is it possible that a B12 deficiency could explain the worsening neuropathy in my feet over the past couple of weeks? Could this be reversed if a deficiency is discovered and treated?

  • acampbell

    Hi Jill,

    It’s a possibility, but this is an issue you should discuss with your physician. He or she should check your blood vitamin B12 level, and possibly do other testing to determine the cause of your neuropathy. Neuropathy due to B12 could be reversible if caught and treated early on, but if it’s been untreated for a length of time, it may not be.

  • Robin

    My doctor would like me to take metformin for my PCOS but I have recently developed tinnitus. Do you think the metoformin will make my tinnitus worse? I took it for a few months before I developed tinnitus (from noise exposure) and did not have any problems. I also searched online for any information about this but could not find anything.

  • Robin

    I also meant to add that I have read that a deficiency of vitamin b12 can be linked to tinnitus, so I am worried that by taking metformin, I will be decreasing my b12 and making my tinnitus worse.

  • acampbell

    Hi Robin,

    I’m not aware of a specific link between metformin and tinnitus. However, as you mentioned, there may be a link between vitamin B12 deficiency and tinnitus. Metformin is an effective treatment for PCOS, so my advice is to follow your doctor’s suggestion. However, you should discuss your concerns about B12 deficiency with your doctor and put a plan in place to have your B12 levels checked periodically. If they are running low, your doctor can prescribe a B12 supplement, if necessary.

  • Robin

    Thank you for your response! I now feel better about taking the metformin.

  • George Morrison

    God Bless your article on metformun vs b12–also
    the article matformin vs Magnesium.
    My wife was hospitilized for 1 week with the Dianosis being Magnesium Deficiency. Every attempt to answer WHY–Released after one week with no solution–except a new regiment of pills

    yes Magnesium Pills at 4times 450mg—but now we know WHY Thanks to the Articles —Patient reduced from 15 mml to 6,5—7.8 over 3 days of intense Dieting including the Vit B12.

    The doctor/pharmacist/Hospital in this case rebuffed by suggestions

    Patient –know thy body
    Doctor—-know thy Patient

  • sharon b

    was diagnosed with type 2 diabetes about 2 years ago. the test was done after a week of celebrating my birth and 45th wedding anniversary, without fasting. the dr immediately put me on metformin, i was so dizzy for several months i could not function. stopped taking the met and recovered fairly fast. i could then resume my schedule of pickleball, walking, riding bike. I am now 69, retired and have lessened my dose to 1/4 pill several times a day. the dr still doesnt believe it was caused by the met. just had a blood test, so we’ll see. thanks for all the helpful info, i have no symptoms of neuropathy at all. i will check the B12 situation.

  • BBrown

    I have been considering trying Glucocil to try to replace Metformin that I have been taking for several years.
    Since that substance also blocks carbohydrate absorbtion would I have the same issues with B-12 absorbtion as Metformin?

  • acampbell

    Hi BBrown,

    Please do not stop taking your metformin without first speaking with your health-care provider. Metformin is a safe and effective medicine for helping to manage diabetes. Glucocil is a dietary supplement that contains mulberry leaf extract, alpha lipoic acid, cinnamon, fish oil, and several other ingredients. I’m unable to find research that this supplement lives up to its claims. But to answer your question, it is unlikely that a carbohydrate blocker, such as this, would interfere with vitamin B 12 absorption.

  • jim snell

    So far and according to actual findings released in January 2013; metformin is the only drug so far that actually bypasses the ampk chain in liver to signal the liver directly to reduce/stop excess glucose release from liver. in my case I actually watched that action on a cgms over a year and a half and could actually time the period from metformin ingestion to when liver reefs back on the excess glucose release.

    Two major issues here is excess glucose release from liver when it is supposed to be fasting and the other is whether one’s pancreas is putting out sufficient insulin.

  • teresaw

    I take glimepiride (not metformin). Does glimepiride hinder b12 absorbtion? I take 2mg with breakfast. My next 2 sugars are in the 50s and 60s, then the next morning my sugar is above 100. Could I take 1mg in the morning and 1mg at night?

  • acampbell

    Hi teresaw,

    To my knowledge, glimepiride, which is a sulfonylurea, does not impair vitamin B12 absorption. I believe this medicine is meant to be taken once a day, but given that your blood glucose levels are low after taking it in the morning, it’s certainly worth asking your doctor if you can split your dose and take 1 milligram in the morning and one with your evening meal. Another option, though is to decrease your dose to 1 milligram in the morning. If your fasting blood glucose is less than 130, you may not need an evening dose. Or, your doctor could start you on another medication, such as metformin. At any rate, talk to him and find out what the best option is for you.

  • Spring

    I have been taking simvastatin for cholesterol but just learned that it probably is the cause of severe leg cramps I have been experiencing. On advice of AARP, I am going to try sublingual B-12, B-6. Folic Acid, Biotin combo to see if I can maintain my cholesterol levels with that. My question is, what time of day should I take it? Simvastatin is taken at night before bed, as cholesterol forms during the night. Should I do the same with B-12?

    Thank you for your response.

  • acampbell

    Hi Spring,

    Please don’t stop taking your simvastatin without first talking with your physician. It’s not a good idea to stop a medicine all of a sudden. And you can’t be certain that the statin is causing your leg cramps. Also, I’m not sure why AARP would advise to take B vitamins to lower cholesterol. The only B vitamin that may be helpful is niacin, but even that is usually given along with a statin. Also, very high doses of niacin are needed (more than what you’d normally get in food or a supplement) to lower cholesterol and this should be given under the supervision of a doctor, as side effects can occur, including muscle pain. You’re much better off (and safer) talking with your physician about other options for lowering your cholesterol, including different medications and dietary changes, such as increasing your intake of soluble fiber and plant stanols, for example.

  • Anonymous

    Dear Ms. Campbell,

    Thank you very much for this great blog and also for continuing to keep this blog post alive for more than 7 years now! It’s been a very informative read – your original post, all the readers’ comments as well as your replies.

    I have a question which I hope you can help clarify.

    Some background first. I am 41, Male, Indian [Asian Indian, not Native American :-)]. Vegetarian (except eggs occasionally), alcohol no more than 3-4 times a year, non-smoker, generally refrain from junk food and from sodas and fruit juices. BMI of 22, though not necessarily athletic.

    I was diagnosed with Vit B12 deficiency around 2010 – level was below 100, around 96 or so. At first I was prescribed oral supplements of 1000 mcg. After about 2 months or so the level did not rise significantly and so I was asked to take injections. I eventually got around to taking injections in early 2012. The dosage was daily for a week, weekly for a month, and then monthly 2 months. The B12 level increased at that time.

    Cut to yesterday, 7 March 2014. I went for a routine health checkup (complete blood count, lipid profile, fasting blood sugar, liver function test, HBA1c, EKG), but also asked for an additional B12 test. B12 level came to 122 pg/ml whereas the normal range marked is 180 to 914. So evidently I am still deficient in B12. And this is borne out by the fact that my symptoms of tiredness, lack of focus, disturbed sleep, etc. are back.

    In the Lipid profile, Total Cholesterol, Tryglycerides, HDL, VLDL and Cholesterol : HDL ratio are all within the mentioned normal range, but LDL is 116 with a normal range mentioned of “<100”.

    Liver function test parameters are all mentioned within normal range.

    But yesterday for the first time my Fasting Blood Sugar (FBS) was above the normal level 133 mg/dL (normal mentioned as 70-100) with HBA1c at 6.7%. Today I went to another lab and did a repeat of both the tests. FBS was 108 while HBA1c is still showing as 6.7%. I am not good at maintaining past records, but I remember for a fact that several times in the past when FBS has been tested during health checkups, it has been within the normal range.

    The doctor whom I consulted yesterday was seeing me for the first time. He has prescribed Metformin 500mg once daily, telling me that I have Type 2 Diabetes.

    The questions I have are:

    1. Could it be the B-12 deficiency rather than diabetes that is impacting my blood sugar levels?
    2.Given my already deficient level of B12, should I start Metformin, or should I first try with diet control, exercise and a repeat course of B12 injections?

    Thanks in advance.

  • acampbell

    Hi Anonymous,

    To my knowledge, vitamin B12 doesn’t affect blood glucose levels, so it seems unlikely that your deficiency is affecting your blood glucose. It’s fairly standard practice now for a physician to prescribe metformin for someone who’s newly diagnosed with Type 2 diabetes. It’s possible that you may be able to manage your blood glucose levels with a healthy eating and regular physical activity. You could talk to your doctor about giving that a try for a month or two and if your blood glucose levels at that time are not within your target range, then you could start metformin. But this is a discussion to have with your doctor. Also, I’d suggest you talk with him about your B12 deficiency and the best course of action to treat this.

  • Anonymous

    Thanks for responding. I watched carbs and sugar for a week and got myself tested again yesterday, though at a different lab this time. Fasting showed up as 90 and PPBS (2 hours after breakfast consisting of cracked wheat and a cup of tea containing milk) showed up as 109. I didn’t get the A1C test done because it’s probably too soon. I am meeting another physician this Monday – a senior doctor recommended by a few people I know. I will definitely mention all of the above to him. I’ll post again about what he says.

    • Wanda

      My name is Wanda I have type 2 diabetes and I’m on metformin 1000 mg 2 x a day and also januvia glipizide lantus injections lisinopril pravastatin I also have numbness on my hands and feet making appointment to see Dr

  • anol

    Iam 34year old unmarried guy. Recently i diagnosed for joint pains found b12 deficincy. My left jnee cap is also slightly bbent Its has been 3 months now took 3 different doses as below
    1 t flexilor p 8, emsulide p , acid grs 20 mg
    2 xenobid 550, lorfit, acera d, defza6 mg
    3 wal d3 60k , bone k2, indocap25, lorfit, rabosure, eldervit 12 inj
    I didnt get relief with thesse medicines but
    Today i suddenly realised that my sex power is gone down .there is no erection what it was earlier.
    Its coz of side efdects of tablets or its a incorrect prescription.
    I am depressed coz of this.
    Please suggest

  • acampbell

    Hi anol,

    I’d suggest that you review all of the medicines that you’re taking with your pharmacist. He or she can let you know about any side effects that could affect sexual function. Also, stress, depression, and anxiety can affect sexual function, too, so if you think that any of these may be an issue for you, please talk with your doctor.

  • bev.

    I have been taking Metformin from mid 2009. It is now April 2014 and I have finally been taken off. I am older, and had almost lost all of my hair. Even my hair dresser noticed. I was sent to a hair specialist 2 time, and blood work was done, I was not tested for lack of b12. So solution was offered. Last fall I started receiving b12 shots and within days their was a peach fuzz in my part and I noticed less hair falling out. I have continued taking the b12 shots and the specialist doctor took me off metformin last week. I am looking forward to wearing hats when I want to not because I have to. Please make the connection between metformin, lack of b12 and hair loss in women.

  • Nancy

    I’m a relatively new diabetic but had an understanding of it before hand as its run throughout my family. For nearly 6 months I managed very well on Metformin, Gliclazide and Simvistatin then suddenly started to experience Hypos which are sudden and frequent. I’ve now had to start on B12 injections and it’s getting kinda scary. My thyroid levels are underactive, I have tested with anemia and I’m so tired that I’m finding it hard to function. Work life is now a joke as I can’t seem to function for any longer than a couple of hours before shutting down.

  • Yogesh

    zydus provide a combination of metformin,glimepride aliongwith mecobalamine.
    Brand name is SUGAMET MCG

  • caroline

    Thanks you for this blog and community. Reading these posts and answers has given me more understanding of the ralationship of metformin and Vitb-12,
    I am pernicious anemia and take daily 1cc b-12 injections but did not know about the metformin-B-12 connection.
    After taking metformin for some time I devloped loose bowel movements and dizziness.
    I find the infot hat b-12 deficiency mimics diabetes very interesting. And maybe valid in my case.
    Should I talk with a hematolgist about my pernicious anemia and thalssemia? I think it could be helpful?
    It there really a way to reverse this horrible disease?It says weight loss keeps diabetes away for sometimes 15 yeaars,but drugs and lifestyle do not do the sameue.. The answer seems in this avenue.

  • A. Campbell

    Hi caroline,

    You’re welcome! I’m glad that you’ve found the blog and community to be helpful to you. Yes, I’d suggest that you certainly discuss your anemia and thalassemia, along with your diabetes with a hematologist and, if necessary, a diabetes specialist. Evidence shows that lifestyle can help prevent Type 2 diabetes (metformin can, as well, but to a lesser extent). However, there isn’t really a way to “reverse” diabetes once you have it. Bariatric surgery, such as gastric bypass, has been shown to lead to a remission of diabetes in some people, but it’s not considered a cure. Many people with diabetes are able to manage it very well with weight loss, healthy eating and physical activity alone. Medication, of course, is helpful, too. It’s a matter of finding out what works best for you. Your doctor can be helpful, as can working with a dietitian. Also, consider looking into diabetes education programs in your community for more information.

  • John R.

    Another doctor beside my diabetic doctor got me on folbic a prescribed medicine. It’s for b6, b12, and folic acid. much stronger than over the counter pills. After 10 years another doctor checked my blood to find it. By the way, I got another diabetic DOCTOR.

  • elizabeth poros

    My name is elizabeth . I have the virus shingles of the face. It affected my eye .spots appeared on hairline and in my hair just on the left side . I was wronyly diagnosed for 8 days. Then was put on medication for 7 days. But one ailment led to another. I now suffer dizziness, weakness in my legs little electrical charges going on throughout the body, but they are becoming getting weaker after 11 weeks. Am terribly constipated and only pass stools if i have HIGH BLOOD PRESSURE. .. HEART BEAT IS FAST AT THIS TIME. HAVE BEEN ADVISED TO TAKE BITAMINS 1. 6. AND 12. BUT MY FERRUM IRON RESULT HAS BEEN HIGH FOR A FEW YEARS. IS THIS ADVISABLE? IT IS 238. AND CAN THE SHINGLE VIRUS INCUR ALL THIS UPSET… PLEASE ADVISE.

  • George Butel

    Oral methylcobalamin is ludicrously cheap at a certain warehouse club, and since, in addition to taking metformin I also take PPIs, which themselves increase the risk of B12 deficiency, I’ve been popping a couple of the methylcobalamin oral tablets every day. Not long ago, I had my B12 level measured, and it was actually well above the reference range. It makes more sense to prevent a deficiency, especially in the case of multiple risk factors, than it does to keep measuring and waiting for a deficiency to occur. Adverse effects of high doses of B12 are incredibly sparse, and, for reasons I won’t go into, it is inconceivable that it could be masking a folate deficiency.

  • Debra Lee Halverson

    Diuretics can cause deficiency like furosemide used for heart failure. If you become deficient from B-12 you probably are in B-1 (thiamin) also. I read a study that said this,,,, Thiamine plays an important role in the regulation of glucose metabolism and pancreatic beta-cell functioning–producing the hormone insulin–and, therefore, diabetes could be considered a thiamine-deficient state. After reading this I decided to give my husband who had been very sick timed release vitamin B complex, the results of his last 2 A1C test were normal and is probably not diabetic any more. I believe medications such as furosemide can cause vitamin B deficiency’s most important thiamin when is comes to glucose regulation.

  • Linda Zimmerman

    I have been taking metformin for several years for diabetes. I take 1 500 in the morning with food and 1 500 in the evening with food. For the past few months I have also been taking glipizide. I do NOT know if I have a vitamin 12 deficiency, however I was tested for a D3 deficiency 9 months ago (upon my request) and found it only 117 so was prescribed D3 drops and my level is now in the 130’s. Several years ago I began to have severe foot and leg cramps (various muscles) mostly during the night but some during the day and I began to take 1000 IU of water soluble Vitamin E daily and it prevents the leg cramps. When I stop the vitamin E, the cramps come back. Is it possible that there is a connection between POSSIBLE deficiency of B 12 with the fact that Vitamin E prevents my leg cramps? My fasting glucose levels are remaining high…. 150-170 range… My A1C has been 6.2-6.9…varies in this range. I have to admit that I do not eat regularly because I lack routine. I eat, but different times of day… Also, I have noticed I don’t like a lot of foods I used to… both in the carb foods and meat… So, not only do I not get hungry, but foods I use to really like does not taste good. I do drink milk every day. What I really WANT to eat are fruits which I limit because of my diabetes… Any suggestions? Oh yes, to help keep my triglycerides down, I take prescription Omega 3 as my liver does not like statin drugs or even Tri-Cor. I also take 100 mg. of ubiquinol daily, 1000-2000 mg of Kelflex generic to control roseacia.. I also am taking a diuretic drug as well as a betablocker. Also, am taking Welchol, and mobic for arthritis… Because of the antibiotic, I take 1 200 mg of fluconozole every other week to prevent yeast infections and have to do that or the yeast infections come back… I do have numbness in my feet but believe that to be caused by back surgery in 2005. But the numbness in my left foot and leg is getting worse….dr. says I have good blood circulation in feet. I also suffer from night sweat and am hormone therapy for that, but still have night sweats….

    • acampbell

      Hi Linda,
      Vitamin E has been known to prevent leg cramps in some people, but I’m not aware of a connection between vitamin E and a B12 deficiency. Because you’ve been taking metformin for several years now, I’d suggest asking your doctor to check your blood level of B12. It’s simple enough to do, and given your leg cramps and numbness in your feet, it’s a good idea to rule out a possible deficiency. In terms of eating fruit, you should be able to fit fruit into your eating plan. Yes, fruits contain carb, but many other foods do, as well, including milk. The key is eating an amount that won’t raise your blood sugar levels. Most people can eat a serving of fruit, which contains 15 grams of carb. A serving is a small apple, 1 cup of berries, half of a banana, or 1 cup of cantaloupe chunks, for example. You don’t mention if you’re doing any form of physical activity, but hopefully you’re able to do some amount, as this can help keep blood sugar levels from going too high. Finally, you may want to discuss your fasting blood sugar levels: as you mentioned, they are on the high side. Talk with your doctor about possible solutions, starting with increasing your evening metformin dose. Keep an eye on any nighttime eating, as well, as this can lead to higher blood sugars in the morning.

    • Cindy

      Whoa, Linda Zimmerman, the well informed doctors and researchers report that anything under 400 is low. You may want to see a neurologist for the numbness in your feet, very likely related to B12 deficiency. Maybe, he will put you on the aggressive B12 replacement therapy that your other doctor has not. As if you didn’t have enough to worry about, you may be deficient in Magnesium also, over 70 % of us are in the U.S. Don’t take my word for it. Magnesium deficiency is also said to cause insulin resistance. Again, don’t take my word for it, the Web is at your fingertips. There are so many resources online that will let you know just how vital B12 and magnesium are to your overall health and well-being. Without magnesium, you have a decreased ability to absorb all the medications and supplements you are on. There are many forms of Magnesium, some that are really good and some that are not so good. Do your homework and find the one that’s right for you if you find out, like so many others of us out here, that you are, in fact, magnesium deficient. If you are looking to lower your cholesterol and triglycerides, you might want to research a natural supplement, Berberine. I like the fact that you are taking Omega 3. You are fortunate that your system does not tolerate statin drugs, have you seen the side effects? Unlike statins, Berberine has no known side effects, though it has been studied a lot. You may want to take a second look at Metformin, some of the side effects that I uncovered in my research are down right scary, including a likely link to vitamin B12 depletion. There are numerous published studies on Berberine. While you are online, take a look. It is touted to stabilize blood sugar and control mad food cravings, while lowering A1C and cholesterol. There are other articles that report that when natural supplements, like iso-quercitrin, L-arginine, rutin, and L-carnitine, are combined with Magnesium, they have been reported to substantially reduce or eliminate “hot flashes”. Good luck to you.

  • Charlotte Parker

    Has anyone heard of Eligen B12? It’s a prescription oral tablet I recently read about that works as well as the IM B12 injection, even if you don’t have intrinsic factor. Apparently it came out a month or two ago

    • CokoBWare

      Why take a prescription when you can take sublingual B-12 called methylcobalamin and get the same desired effects? Also, B-12 can help with chronic anxiety issues. Five people I know who’ve taken it for anxiety have seen a major decrease in anxiety symptoms. In addition, a quick web search for B-12 and anxiety should give you some great info.

      • J-dawg

        Well, for one, going the prescription route allows you to discuss it with your doctor and gives a professional the chance to weigh whether it’s a good idea for you or not. For another, prescriptions are often covered by health insurance whereas OTC self-prescribed remedies usually are not.

  • Mary Feagins

    after being on Eat to Live plan (Dr.Joel Fuhrman) I no longer need diabetes meds or arthritis meds. It is a difficult plan and includes fasting. If you can manage to do it, I definitely recommend it. I feel so much better; A1c went from 6.0 to 5.3. Kindest regards and good health to you all.

    • Reb

      Please what is the meaning of Eat to Live?

  • Mavis

    Just stumbled upon this sight this weekend. I need to add another layer to the discussion. In addition to diabetes I was also dx with MS 17 years ago. I believe that my having diabetes was helped along by being treated with steroids for the MS. Several months ago I had what I thought was a MS flare. It started with numbness in both my feet. That was unusual because my Ms usually started on one side. Long story short it has been over six months and the numbness is still severe, traveling up my legs, and into both my hands. I did not take the course of steroids because I didn’t want to aggravate the diabetes. have been on metformin about four years and my dose was increased about a year ago to 1,000 mg a day. I met with my diabetes dr this past Thursday, complained that the numbness was worse and asked COULD it be from the diabetes. She said it could but she didn’t believe it was. In passing she asked had I ever had b12 shots but we didn’t continue with the topic. From desperation I googled metformin and side effects and this article came up. Today is Sunday and tomorrow can’t get here fast enough. I will be calling office first thing in morning to request blood test for b12 deficiency. In my heart of hearts I do not believe what I am experiencing is just an MS flare up.

    • acampbell

      Hi Mavis,
      I’m glad you came across this metformin information and I hope you were able (or will be able) to get your vitamin B12 level check. Keep us posted on how things turn out.

      • Mavis

        accampbell. Thank you for your response. This is a sleepless night and I’ve stumbled on this site again. Since I was here before I was admitted to the hospital. Treated for UTI. Numbness is still pretty severe and disturbing. Just today I was seen by my primary and was prescribed b12 to use under my tongue daily as well as a large dose of vitamin d, taken once a week. Will have to see if there is any improvement. Still don’t believe all these sensory issues are only MS. Will have to wait and see. Will bookmark this page so I don’t have to keep “stumbling” on it. Lol.

  • jelly jen

    i have PCOS and ive been taking metformin since last year with folic acid and vitamin e… any side effects or is it okay to continue taking it…

  • Donna Medley

    I am excited and encouraged to hear about this body shape idea. I am pear shaped, and struggling with controlling my diabetes, and also have just been prescribed Lisinopril (5mg daily), for kidney damage. My reading for protein in urine was 3.0!! I’d also like to lose more weight. I fight wanting to eat pretty much all the time. I’ve been on metformin for about 15 yrs,(1000 mg. twice daily), and also take Glipizide twice a day, Coreg, and Effexor. Effexor is for Fibromyalgia. My A1c is 6.3. Dr says that’s normal, but I really want to get lower and off, part of my meds if not all of them. What about frying lightly (cornmeal) breaded catfish in coconut oil? Will that be acceptable? I use coconut oil for most everything. Got rid of Canola oil. Thanks.

  • J-dawg

    This article says nobody knows why this happen, but other academic literature indicates that there is strong evidence it happens due to interference with calcium-assisted absorption in the small intestine, and that taking a calcium supplement can help.

  • Pervaiz

    I am diabetes type 2 and use the medicine metformin 500mg twice daily including only one tab of 2 mg

    • Roger Daniels

      Check out Berberine as a replacement for metformin . In tests
      Berberine has done just a good as metformin without the side effects.
      Doctors will not precribe it because it is a natural product.

      • American Dox

        Doctors have NO INCENTIVE to prescribe drugs. We do not get paid for prescribing drugs. We do not get kickbacks unless we enjoy going to federal prison. We prescribe what works. We also prescribe diet, weight loss, and exercise.
        Metformin works and has been proven to work by multiple large scale studies.
        Typically we suggest that patients take a vitamin for B12….OH WAIT! OH MY GOD! NOT A VITAMIN! Nevermind, a vitamin is a “natural product” so you can be sure that your doctor would NEVER suggest it. In fact, vitamin B12 is all natural and there is NO WAY any doctor would EVER give you a shot of B12, because, you know, it is a natural product.
        Take off your tin foil conspiracy hat.

        • Betsy Kay

          Hello American Dox,

          I posted a few sentences on the Metformin and Risk For Vitamin B12 Deficiency blog site last night. I am not a doctor, but I would just like to say that after years of trying to find one that will prescribe “natural” medications, for example Armour Thyroid, I continually hit a brick wall. Just like your post saying that b12s are, “all natural”. They are NOT. There are many synthetic b12s that are not natural supplements on the market today. Suggesting a patient supplement with b12 and not directing them to find the ones that are “active” natural versions COULD be detrimental to their health, especially with people like me that have a mutation that doesn’t allow my body to absorb the supplements correctly. Another example would be folic acid, which is also a synthetic supplement that takes more conversions for the body to convert it to active folate. Metformin is being taken by two people that I love dearly. Both, possibly, have extreme side effects from the Metformin medication. One of them has been on it for years, and the other started the medication recently. I am not an expert, nor do I have any credentials relating to this subject, but I am trying to educate myself regarding b12 supplementing for my own health and the health of the ones I love. I am NOT criticizing the medical community, I am trying to find answers and solutions. I am pretty sure that one of the, “active” forms of b12, is indeed being used in b12 injections. But, suggesting a patient supplement with b12s can lead to the common use of the synthetic versions mostly available on the market for the least amount of money. It is also important to acknowledge that all supplements are man-made, I am living proof that the active forms of supplements and medications work better for ME. But, please don’t blanket all b12s as “all natural”.

  • Angie Bloodsworth Wilkins

    I am type2…for 20+ years. I’ve been taking Metformin for the last 6-7 years and now I am b12 deficient–out of the blue. Can’t hardly keep my head up…sleeping a lot. I go to my primary tomorrow to find out about B12 injections but this is ridiculous.

  • Betsy Kay

    I just wanted to clarify that some b12 supplements are NOT all natural. Some common b12 supplements are man-made versions and not the active version of b12. “Cyanocobalamin is a synthetic form of vitamin B
    ₁₂.” as are all the b12s, I believe, that start with “cy”. The active b12s, from what I have read, usually start with, “Methyl”. There are also b12s that start with, ” hydroxy “.

    There are differences in b12 supplements that might make a difference on how a person’s body processes the supplement. Most everything I have read, suggests using the active form of any supplement and not the man-made/synthetic forms. The synthetic versions usually require more conversions than the active versions before the body can use them. The idea is that the synthetics will convert easily, but in some people that does not happen efficiently. I have a MTHFR double mutation. I am a perfect example as to why… sometimes the man-made versions don’t work at all, or well.

    • Frank Hollis

      Methyl, cyano, hydroxo are all made in the sdame vat by the same bacteria.

      Methylcobalamin is no better than other forms…

      • Betsy Kay

        Hi Frank,

        Thank you for responding. The difference is in the amount of conversions that need to be done in the human body with the synthetic forms. If the body is working correctly, the synthetic forms will probably accomplish the desired outcome. But when it is not, as is the case with me, the body can not process the b12s in a synthetic form (or most other synthetic supplement forms of different vitamin supplements) correctly. Therefore, less chance they will be absorbed, or work at all, in instances like mine. In my personal experience, the methyl form of b12 works better for me. It is my understanding that the methyl form of b12 does not require the additional conversions to be absorbed. Similar to my family’s inability to use synthetic thyroid medications. Our bodies, can not process them. We need to take a natural thyroid medication, like Armour Thyroid, vs Levothyroxine. The Levothyroxine does not work, and creates additional health issues for us. The synthetics apparently do not convert correctly in our family’s bodies. The Levothyroxine is a synthetic form of thyroid medication that requires additional conversions in the human body to be processed correctly. When that’s not a problem, the synthetic versions should accomplish the desired, necessary outcomes. There are many, many people that take the synthetic forms, and do quite well on them. I am not one of them. B12s are not created equal for me.