Do You Know Your Insulin Level?

People often keep close watch on their glucose numbers. But how many of us know our insulin level? Dr. Joseph Mercola says fasting insulin is “the number that may best predict your sudden death.” Sounds important. But what does it mean?

Our bodies need some circulating insulin at all times, even when we don’t eat. Otherwise, our livers keep making glucose and dumping it into the blood. Livers do this to prevent blood glucose from going too low.


So a fasting insulin level should never be 0, which it might be in a person with untreated Type 1. It shouldn’t go below 3. But a high insulin level is just as problematic. A high insulin level is a sign of insulin resistance or prediabetes. It can also signify early-stage Type 2.

According to Dr. Mercola, too much insulin promotes weight gain by storing fat. It promotes insulin resistance, lowers magnesium levels, and increases inflammation. It also tends to lower HDL (“good”) cholesterol and raise levels of LDL (“bad”) cholesterol.

All of these increase the risk of diabetes and heart disease. It may be that high insulin levels come before insulin resistance and help cause it.

If you already have diabetes, why should you know your insulin level? Mainly, it helps diagnose what is happening with you. Your blood glucose may be high, but how much of the problem is too little insulin? How much is insulin resistance?

A fasting insulin level test is valuable in several situations:

• Diagnosing prediabetes and metabolic syndrome. “Prediabetes” is one result of insulin resistance (IR). IR causes high cholesterol, high glucose, and high blood pressure. A high level of fasting insulin indicates IR and can encourage a person to make changes to lower it.

• Separating Type 2 from LADA (latent autoimmune diabetes of adults). A person with Type 2 might have a normal or even high fasting insulin level. A person with LADA is typically low.

Why does it matter? A person with LADA is more likely to benefit from insulin injections. He may be able to avoid years of oral medications that don’t help him much.

• Seeing if a person diagnosed with Type 1 is still making some insulin. A recent study from the UK found that about three quarters of adults with Type 1 actually produce small amounts of insulin. Knowing you have some good beta cells can affect therapy and give some hope of improvement. So an insulin level test could show you if you have some.

This finding also calls for more research. Why do some beta cells survive and function normally when most have been destroyed?

What should your numbers be?
Insulin is measured in “microunits per milliliter” (mcU/ml or mIU/ml). Unfortunately, there isn’t much agreement on what level is ideal. The Web site Health Central says 10–20. Dr. Mercola says less than 5.

A study in Arizona found that women with a fasting insulin level around 8.0 had twice the risk of prediabetes as did women with a level around 5.0. Women with a fasting insulin of 25 or so had five times the risk of prediabetes.

University of Washington researcher Stephen Guyenet writes that

The average insulin level in the US is 8.8 mIU/ml for men and 8.4 for women. Given the degree of metabolic dysfunction in this country, I think it’s safe to say that the ideal level of fasting insulin is probably below 8.4 uIU/mL…[Best] would be 2–6.

How to lower insulin level
Lowering insulin levels seems pretty similar to lowering glucose. Authorities like Dr. Mercola say the key is to reduce intake of sugar and grains. Those foods stimulate insulin production. Refined grains and fructose-sweetened drinks are the worst, he says. Better to eat fats and proteins.

Writing on, Andy Jackson has a somewhat different take. “Increase your intake of fresh fruits and vegetables, whole grains and lean proteins,” he says. “Avoid processed and fast foods, which are high in sugar, fat, and salt.”

Exercise also lowers insulin levels and insulin resistance.

So ultimately, testing for insulin levels isn’t an earthshaking idea. It’s mainly important for diagnosis, especially of LADA. It’s also a powerful screen for risk of Type 2.

Since most people with or without diabetes have never had the test, it may be worth asking for. You’ll get a better idea of what’s happening with you. But for day-to-day monitoring, glucose testing is just as good as insulin testing.

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  • Terri

    Now that is some interesting and vital information! Isn’t the human body a marvel? Now if more health care professionals would educate us about this all important factor…

  • Dariusz

    Authorities like Dr. Mercola” and here i stop reading if you rally reference hi then whole article as big nothing read opinion about mercola he is salesman he for example change his opinion about iodine 3 times magnesium sterate and many many others story

  • Craig

    You lose me when you referenced Mercola. He’s a quack.

  • Mark

    Dr. Mercola is anything but a quack. He is an MD and researcher who is evidence based (scientific) and provides research results to back up his conclusions. He is also continually adjusting his conclusions as new research comes along. Is anybody is a quack, it is you Craig.

  • Jamal

    My wife age is 34 years, her insulin fasting result is 19.82mul
    Pls advise

    • Michael Gaines
    • Michael Gaines

      That’s on the high side of normal. But that means she is leaning towards insulin resistance.

  • ashley

    I just had a fasting insulin test about a week ago andmy insulin level was 182 they ended up putting me on 1000 mg of metformen a day

    • Michael Gaines

      The issue is carbs. Move to a ketogenic diet. I’ve been off insulin this entire week since adopting a ketogenic diet. I’ve gone from 4 to 5 injections a day to 0. I’ve had glucose readings over 300 on a normal diet and with insulin keeping my averages in the 140 to 150 range.

      Once I got into ketosis about 3 days of effortless eating, my blood sugars began to normalize. My average glucose for the week is 125 without any insulin whatsoever…

      Insulin is your enemy in to large a quantity. Most insulin resistant people secrete to much insulin and all that excess is our problem…

      You need to convert into an effective fat burning machine because you certainly are not an effective sugar burning machine…

      Watch this video to expand your knowledge.

    • Michael Gaines

      I think you mean your sugar level was 182 not insulin level. Ketogenic diet is better than drugs.

  • Gaby

    My insulin is 4,2 and I have hypoglycemia and diabetes symptoms: hunger, thirst and excessive urine. Physicians don’t pay attention to my synptoms but I don’t feel well specially if I don’t eat often. I feel dizzy, have palpitations and feel like I will faint.

    In the last blood tests the glucose level before the glucose tolerance exam was 89 and after taking the glucose it dropped to 68.

    Should I insist on this aspect, or is it normal?

  • Silvia

    I’m 15 and I haven’t had my period in a year. I just got the call from the doctor and she told me I have insulin resistance and that my insulin level was 160. My mom told me that diabetes runs in the family. I’m scared of what my future is.

  • meagan

    I just my fasting insulin results come back with reading 30.7, the reference range on the test says 2.0-19.6. Then under all the numbers says ” This insulin assay shows strong cross-reactivity for some insulin analogs (lispro,aspart, and glargine) and much lower cross-reactivity with others (detemir,glulisine). Can someone help me understand this please? I am so confused and concerned. My A1C was 5.6 which was normal and cortisol was 7.6 and test showed it was normal. My primary is setting me up with a endocrinologist, but I want to know what to expect and to ask when I go to meet this new doctor.

    • David Spero RN

      Meagan, as I understand “cross-reactivity,” it doesn’t matter unless you are actually taking that drug. If you’re not injecting insulin now, 30.7 is high and might mean you are at risk for diabetes. Your A1C is also getting close to borderline diabetes. I don’t know what the endo will say, but he might want to start you on metformin. I would ask if you need more work-up for prediabetes, and ask for information explaining these labs. It sounds like healthy behaviors like those on our website would be the best plan.

      • Alix

        Hi David Spero, you sound like you really know what you’re talking about. My situation is similar to the above scenario. My fasting insulin came back In Range @ 10.0 and the reference range is 2.0-19.6. Below it says the same thing “this insulin assay shows strong cross-reactivity for some insulin analogs (lispro, aspart, and glargine) and a much lower cross-reactivity with others (detemir, glulisine). The results had a note off to the side that said ” this checks out higher than it should, start taking Metformin”. I don’t understand why I would need to start a medication when the results are in range?

    • vrm

      You should change your diet quickly, IMO. I got to much more stable sugar levels ( and even my triglycerides lowered dramatically) after cutting carbs from diet significantly. Talk to your doctor about diet/exercise BEFORE you go on metformin or other drugs. Drugs lead you down a slippery slope where you become complacent and do not modify your lifestyle, which caused your problems in the first place. Lot of people going on metformin eventually end up taking insulin rather quickly. Behavior modification may delay that significantly and possibly stave it off altogether.

      • Michael Gaines

        Agree 100%!!!

        12 weeks insulin free now eating ketogenics. I’ve eliminated over 440 insulin injections just eating high fat, moderate protein and low carbohydrate.

    • Lisa

      Hi Meagan, how did everything go…we have similar numbers…went to a hormone therapy place to get fixed lol.

  • Adolfo Vasquez

    Hello I’m Adolfo I’ve been having the black mark on my forehead for the past 7-8 years cones on and off but I read the article saying it’s some sort of pressure diabetes and it run in my family. I just need to know if I need to go to the doctor again because he just gave me some cream to put on it but sometimes that doesn’t even help.

    • David Spero RN

      Adolfo, I wouldn’t assume diabetes from a black mark on your forehead. If you have other symptoms, or if you have had high glucose levels on a test, then I would worry. Like anyone else, you should be eating healthy food (very little refined carbs), moving your body, and reducing stress.

      • Adolfo Vasquez

        Okay I work out a lot and started to eat healthier but it seems to appear no matter what it’s kind of like a dark purple color when I sweat I wipe my forehead and it comes off but not always

    • vrm

      It is possibly due to acanthosis nigricans, caused by excess circulating insulin in the blood. Skin tags, skin darkening/thickening are typical symptoms of insulin resistance. If it disappears in your case, you are lucky- for many, it doesn’t. Talk to your doctor about it.

  • SugarKillsAll

    Insulin will always be raised when you have issues in your body that requires replacing cells. The more cells destroyed the more insulin and glucose. You also see higher ldl levels. So to use it for type 2 screening can be incorrect.


    my friends sugar level is 26.6 had to send her to hospital a few minutes ago.

  • Dawn Fuller Wall

    My daughter is 16 years. Old and had to do a fasting before her blood work. When the blood work came back I got a call telling me her Insulin level was 58.7. She is being referred to an Endocrinologist. I’m very worried as she is too. The Dr. Office said if we haven’t heard from the Endocrinologist’s office in 2 weeks to call them back. What does this level mean ? I know they said normal is 2.0 – 19.6. They just said it means she definitely has something going on with her Pancreas.

    • David4Peace

      Dawn, the endo should be able to answer your questions — the most likely cause of high insulin is high insulin resistance. Your daughter is at risk for Type 2 diabetes and polycystic ovarian syndrome (PCOS), but they can be prevented and/or managed. Once you know what’s going on, you can research it. David Spero RN

      • Dawn Fuller Wall

        Thank you so much David Spero.

    • Aisha Shepherd

      try a pituitary tumor. have your endocrinologist to test your prolactin levels. They should range from 3 – 30.

  • Achsah Chiasson

    Hi, I did blood work after my gyno apt. I am 26 and miscarried in feb. 2015 <5 weeks. I had two normal periods then the third month and now onto my 5 month Ive had normal periods but break through bleeding around my ovulation. Gyno did ultra sound. Thick utural lining and r cyst on overies and blood work. Everything came back normal except my free insulin is 99h and my total insulin is 126h. She sent me to my family Dr BC she says its out of her scope, as in nothing to do with my female problems. Family Dr. Referred me to endocrinologist, which I'm still waiting for an apt. ( was told to give two weeks then call, same as lady above) question is, pcos should have been tested with my blood work at my gyno?

    • Aisha Shepherd

      Endocrinologist may treat you for a pituitary abnoma, which is a tumor on your pituitary gland. Inquire about a cat scan or mri on your brain. Exercise and try to decrease your ph levels. decrease most of your levels, glucose, insulin, ph, bmi, etc..

  • Achsah Chiasson

    Hi, I did blood work after my gyno apt. I am 26 and miscarried in feb. 2015 <5 weeks. I had two normal periods then the third month and now onto my 5 month Ive had normal periods but break through bleeding around my ovulation. Gyno did ultra sound. Thick utural lining and r cyst on overies and blood work. Everything came back normal except my free insulin is 99h and my total insulin is 126h. She sent me to my family Dr BC she says its out of her scope, as in nothing to do with my female problems. Family Dr. Referred me to endocrinologist, which I'm still waiting for an apt. ( was told to give two weeks then call, same as lady above) question is, pcos should have been tested with my blood work at my gyno?

  • Julie

    So, why would one have a LOW insulin level (3.8) but high glucose levels (A1c = 5.7)? It doesn’t make sense to me…

    • David Spero RN

      Julie, it sounds as though you may not have enough insulin. You may have LADA or MODY, as discussed in the article. I would ask your doctor; you might benefit from insulin or perhaps from bitter melon or vinegar, as I often write about.

  • Cherise Jacqueline De Meyer

    Hi I did a blood fasting test and got my results back from the doctor, my insulin level is 38 and he says this is very high. Can someone please explain to me better on what this means? I only missed my period 2 months but then it came back, will i still be able to fall pregnant with this high level of insulin? Am a n pre-diabetic ? thank you so much

    • David Spero RN

      Cherise, it seems you are insulin resistant. You may or may not have PCOS or prediabetes. I would advise you to treat yourself as if you had diabetes — exercise, reduce carbs, reduce stress, ask about metformin, and see a doctor who knows about your kind of situation.

  • Roni Marie Byvoets

    I just got my blood fasting Insulin results back and mine is 1.0 . I am honestly lost on the results can anyone explain. Thank you.
    range 2.0 – 19.6 mclU/mL
    my result 1.0

    • David Spero RN

      Roni, are you having symptoms of diabetes such as thirst, frequent urination, fatigue, perhaps weight loss? Your level is low, which might indicate early stage LADA or Type 1. Please ask your doctor what it means for you.

  • J L De Foa, MD

    Mr. Spero: “diabetes mellitus” is latin for “to go through” and “honeyed” or more colloquially “sweet pee”, the modern (latin) replacement of which is “glucosuria.” Both terms are of limited clinical utility, as they identify only a clinical sign, not the disease mechanism. So instead we should talk about hypoinsulinemia and primary or secondary hyperinsulinemia. Hypoinsulinemia, aka Type I DM requires insulin to avoid death. Primary hyperinsulinemia is due to an insulinoma (rare), while iatrogenic hyperinsulinemia occurs with exogenous administration such as accidental or deliberate “overdose”. Secondary hyperinsulinemia is without a doubt the RESULT, not the cause, of insulin resistance. When insulin sensitive cells don’t respond to normal levels of insulin the pancreas must increase production to avoid hyperglycemia. Years of elevated insulin production – reflected by elevated baseline/fasting insulin levels – leads to tired out pancreatic beta cells and relative or absolute beta cell failure. Flogging a tired pancreas with metformin and other insulin secretagogues possibly only hastens that process. THE ONLY WAY TO REDUCE INSULIN REQUIREMENTS IS TO REDUCE CARBOHYDRATE INGESTION. Eat a banana, drink a Coke, need insulin. Eat less, drink water, need less insulin. In summary, Type II DM is a LATE indicator of likely decades of increasing insulin resistance. A 12 hour nightly fast will trigger glucagon to rise to maintain normoglycemia from stored glycogen and allows insulin levels to fall to normal baseline levels which likely helps prevent peripheral insulin resistance and simultaneously letting pancreatic beta cells rest.

  • Guest

    Since fruits make my blood sugar skyrocket, should I continue eating them? It seems like I should avoid foods that make my blood sugar go way up. Also, fruit makes me crave sweets so I honestly don’t see the value in eating fruit.

  • Guest

    Thanks David. My doctor felt the same way: just avoid foods that cause blood sugar spikes.

  • Sewpeggyc

    I have an insulin level of 5 and my c-peptide is 1.2
    I had gd during 3 pregnancies then was diagnosed t2 after the birth of my last son. Been being treated as t2 for 6 years. I’m 5’6″ and weigh 125 lbs. I don’t have any family history of t1 or t2. I’m wondering if my insulin and c-peptide levels would warrant a LADA diagnosis? My antibody test came back negative and that is confusing me. I was also diagnosed with Sjogren’s Syndrome earlier this year which is also an autoimmune disease.

    • Sewpeggyc

      Just realized that the negative antibody test is actually an insulin antibody test.

  • Monique Williams

    I have an insulin level of 234 glucose level of 88 and A1C of 6.8 and this was not fasting what does that mean?

    • David Spero RN

      Monique, you don’t say if your insulin level was a fasting test. A random insulin level doesn’t tell you much, but your A1C of 6.8 indicates diabetes, though a glucose level of 88 is OK. Follow up with your doctor Fasting or eating doesn’t affect an A1C.

  • Tersia Otto

    is a 14.5 result normal for a random insulin test? how do i know if i am insulin resistant?

  • Tersia Otto

    random insulin test result 14.5. normal?

    • David Spero RN

      Tersia, Unfortunately a random insulin level doesn’t tell you much — it depends on what you have eaten. You may want to go back and get a fasting level. Monique, your A1C of 6.8 indicates diabetes, though a glucose level of 88 is OK. Follow up with your doctor Fasting or eating doesn’t affect an A1C.

  • Majdi

    My Fasting insulin test is 29.2 uU/mL, am I insulin resistant? or High? Fssting Blood Sugar (Glucose), Serum is 121 mg/dL???

    • David Spero RN

      Majdi, 29.2 fasting is quite high. Probably you are insulin resistant and prediabetic, because a fasting glucose 121 is close to diabetic range.