Diabetes Self-Management Blog

Blood glucose monitoring is an important part of managing diabetes, but according to a new study in the journal Diabetes Care, failure to take the simple action of washing your hands with water before pricking your finger could result in falsely elevated readings.

Cleaning the finger with an alcohol swab prior to taking a blood sample is commonly recommended as a way to make sure the test site is clean. To determine whether alcohol swabbing effectively removes fruit residue, researchers at the Juntendo University Graduate School of Medicine in Tokyo measured the blood glucose levels of 10 volunteers without diabetes under a variety of conditions. As a control, the participants’ fingers were cleaned and a fingerprick check was conducted to determine their true blood glucose levels. The volunteers then peeled either oranges, grapes, or kiwis, and then had their blood glucose checked immediately, after swabbing with alcohol, and again after washing with tap water.

The researchers found that when the volunteers’ hands were cleaned with tap water, their blood glucose readings matched their readings prior to peeling the fruit, generally around 90 mg/dl. However, when their glucose levels were measured immediately after peeling the fruit, on average their readings shot up to 170 mg/dl after peeling an orange, 180 mg/dl after peeling a kiwi, and 360 mg/dl after peeling a grape, respectively. And even when they had swabbed their fingers with alcohol — in some cases as many as five times — prior to the measurement being taken, the readings still remained elevated over their actual blood glucose level.

In an interview with Reuters, Robert Cohen, MD, an endocrinologist who was not involved in the research, noted that “People are used to pricking the finger, drawing a blood sample, (and) assuming that the measurement they make reflects the sugar content in the blood.” But, he contends, people “really need to have a checklist” to ensure the most controlled monitoring environment possible and, consequently, the most accurate results possible.

According to the authors, the take-home message is to wash your hands with tap water instead of relying on alcohol swabs before checking your blood glucose — particularly if you have been handling fruit.

To learn more, read the piece “Fruit salad and blood glucose meters don’t mix” or see the study’s abstract in Diabetes Care. And for tips on getting an accurate blood glucose result, check out “Making Your Meter Work for You.”

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Comments
  1. Music to my ears and a beef!

    Yes cleaning fingers before doing finger stick is an important detail.

    The absolute failre to address all the reasons for high/faulty strip readings is unhelpful.

    As one who has done 20+ sticks a day especially to look at lows and bg descending, this artticle needs to be more explanitory.

    After walking; I can see good tracking on all fingers within 2 to 5 points.

    After sitting, I will see 10 to 20 point spread.

    If I do not get good flowing strike and miserly amount of blood, readings can be 100 or more points herat stopping off.Bad strios same readings. COntrary to industries protestations, it is not perfect strip test every time.

    I had to give up on one meter as it was aleays 2 x off whne I was not solidly hydrated. Drink large glass of water each time before test.

    So far the only strips and meter technology that can give me good ( not perfect - some times a 100 points off) is the FAD-GDH technology and meter. See report from Kobe niversity.

    ANother famous name brand I use out of couriosty tracks well till my gut digests food products from famous grocery store - 2 hours after digestion and then lasts 4 to 6 hours - 20 to 100 points off cal.

    FDA has its head inplaces less suitable to help s diabetics.

    The other times for me when I get heart stopping numbers is right after munching 4 - glucose tablets to stop low and look out till heart has had chance to mix the sugar and blood by pumping around the body a number of times to dilute and mix the sugar.

    I will see this on liver dump whne BG shoots up to 511 and slides back to 254 to 278 as glucose remixed. Liver and stomach just shoot that crap out as fast as its capability allow - not evenly mixed like car injector - carberater. High readings you bet - transport - not averaged blood readings.

    Generally I find one from each hand and averaged is good first shot. If I need to cal CGM I take 2 from each hand - different fingers and averaged. I get very good tracking of CGM and handheld that way.

    Put me down as fed up with the mush ball pablum from the industry that struts around as informaion as less than helpful.

    Posted by jim snell |
  2. corrected spelling - please ignore prior response

    Music to my ears and a beef!
    Yes cleaning fingers before doing finger stick is an important detail.
    The absolute failure to address all the reasons for high/faulty strip readings is unhelpful.
    As one who has done 20+ sticks a day especially to look at lows and bg descending, this article needs to be more explanatory.
    After walking; I can see good tracking on all fingers within 2 to 5 points.
    After sitting, I will see 10 to 20 point spread.
    If I do not get good flowing strike and miserly amount of blood, readings can be 100 or more points heart stopping off. Bad strips same readings. Contrary to industrie’s protestations, it is not perfect strip test every time.
    I had to give up on one meter as it was always 2 x off when I was not solidly hydrated. Drink large glass of water each time before test.
    So far the only strips and meter technology that can give me good ( not perfect - some times a 100 points off) is the FAD-GDH technology and meter. See report from Kobe university.
    Another famous name brand I use out of curiosity tracks well till my gut digests food products from famous grocery store - 2 hours after digestion and then lasts 4 to 6 hours - 20 to 100 points off cal.
    FDA has its head in places less suitable to help us diabetics.
    The other times for me when I get heart stopping numbers is right after munching 4 - glucose tablets to stop low and look out till heart has had chance to mix the sugar and blood by pumping around the body a number of times to dilute and mix the sugar.
    I will see this on liver dump when BG shoots up to 511 and slides back to 254 to 278 as glucose remixed. Liver and stomach just shoot that crap out as fast as its capability allow - not evenly mixed like car injector - carburetor. High readings you bet - transport - not averaged blood readings.
    Generally I find one from each hand and averaged is good first shot. If I need to cal CGM I take 2 from each hand - different fingers and averaged. I get very good tracking of CGM and handheld that way.
    Put me down as fed up with the mush ball pabulum from the industry that struts around as information – nee lawyer’s statements as less than helpful.

    Posted by jim snell |
  3. I wash my hands with some detergent and wipe in a clean paper towel when ever possible. I don’t think alcohol does anything useful.

    Posted by calgarydiabetic |
  4. Forgive me for being simplistic but the A1C result would be a better indication, yes?

    Posted by CentralCaliforniadiabetic |
  5. I don’t wash mine at all.Never have. No trouble with my sugars..if I eat fruit I would wash my hands after that anyway. Try finding a tap in a train, uni lecture, bed..just not practical.

    Posted by CAthy |
  6. I agree 100%. Not enough has been said about cleaning off the site where the blood sample is taken. These days i consume more fruit than i ever had even before i had diabetes.I was shocked at some readings in the high 100’s or even in the 200’s. After seeing these readings i cleaned off my fingers and retested. I knew the numbers were incorrect from the way i felt and prior history. Sure enough my second readings were 111 to 130. Using clean tap water to clean test sites should be talked about more often than it is. I have been testing for about 5 years now and had questioned some results. Now i know for myself especially after reading it here. Thank you…Ed Greene

    Posted by Ed Greene |
  7. In response to CentralCaliforniadiabetic: According to the Mayo Clinic Web site “The A1C test result reflects your average blood sugar level for the past two to three months” (http://www.mayoclinic.com/health/a1c-test/MY00142). Since it does not measure your actual blood glucose level at the time the test is taken it is not suitable for determining if immediate corrective action is needed for a high or low blood glucose level. Taking an A1C test more than once a month is probably not useful (even that may be too frequent); most diabetics take a blood glucose test two or more times a day.

    Posted by Gary |
  8. I’m with Jim in his comments. I have been doing this since 2008 when I was in the Hospital for a whole week. I do not want to go back, but am STILL confused about how to tell where I am with this testing strips.

    I have switched brand meters for insurance purposes and bad readings already, but still am not sure where I am. I have also switched from taking insulin shots to pills but cannot seem to get below 130 on a good morning. And I do not seem to find out how normal or bad it is. The rest of the day seems okay, but I do not seem to feel as good as I used to though.

    The thing Jim said about water and walking seem to be my case as well. Does anyone have any sugestions? Diabetes, to me, does not seem to be my doctor’s strong suite, but he is alright otherwise.

    I am also over 55 and not fully employed, with my wife’s insurance being the only one we can get. I have looked for my own, but most people have said since I am type 2, I am not touchable with my own insurance. I would like to let her NOT have to work for the insurance reason only, but have not found out how to do it.

    Thanks for letting me vent a little, it’s 4:30 in the A.M. and I can’t sleep, so I took to reading some mail.

    Posted by Henry Rutledge |
  9. we should always wash our hands Before beginning to handle our blood testing equipment .That is using good hygene ..

    Posted by Maria Huff |
  10. I am a diabetes educator and I did my own experiment at work with hand washing and eating fruit. I actually ate grapes, my fingertips were sticky with grape juice residue and I check my blood sugar after eating the fruit. It was 200. I then washed my hands with soap and water and re-checked my blood sugar and it was 105, a 95 point difference with hand washing. I did not use alcohol to clean my hands to compare but will re-do that experiment soon. I tell all my patieints that the best way to have a clean surface is by warm water and soap. Thanks for sharing this info.

    Posted by Mary Coates |
  11. When I was first diagnosed (two years ago last month), I was told to use alcohol to clean the test site. Shortly afterwards, during my Diabetes Awareness class, the instructor told us that was actually a bad idea due to the fact we may get inaccurate readings. I have been washing my hands prior to readings ever since, when possible. As one poster said, it’s not always feasible, so I carry either hand sanitizer gel or wipes. Not the best alternative, but, hey, we do what we can, right?

    Posted by Cynthia |
  12. I’ve also found if I don’t wash after putting on hand cream I get high redings

    Posted by Cheryl Jordan |
  13. By washing hands with warm water and soap, you increase blood supply to finger tips thereby making it easier to get a drop of blood. NOW when traveling, taking the premoistened wipes you can get in travel size. And then use dry tissue to dry hands before sticking.
    As far as manufacturers “knowing what is best and what to do”????? Remember they are in it for the money to their expertise. Live and learn

    Posted by Susan |
  14. A method I use to partially compensate for a lack of water to rinse off a test site is to squeeze out a much larger drop of blood than needed by the meter. Then the blood drawn into the test strip has not touched the surface of the skin or mixed with sweat that might contain sugar residue. That also has the side-benefit of better flushing out the lancet puncture site. That approach works well during a hiking trip or long cycling trip.

    When travelling, I always carry water to ensure good hydration in conjunction with Type-2 meds. That water also provides the means to rinse lightly outdoors or into a waste receptacle indoors where there is no plumbing available. Every eating establishment makes drinking water available, so that can be used to rinse when you don’t have your own.

    Posted by Mark41 |
  15. i was diagnosed in 1985, since i was 5 years old. i have never really washed my hands before testing, but lets have some common sence first. anything on your fingers has a posibility of causing bad results. fruits have a high sugar content compared to other things around. trust how you feel. if you dont trust a result, try again. i wipe my fingers off-(mostly on my jeans- before i test. if i dont trust the results, i retest. i have had good luck in the past and will in the future. what works for one person/doctor is not always the same, find what works for you.

    thank you.

    Posted by Mike |
  16. With Diane Fennel’s utnost patience and forebearance; I would like to respond to Henry Rutledge - prior writer to DSH on this blog:

    First off as member of great unwashed and layman I am not competent to advise you - that has to be between you and your advising experts:

    That said:

    I end up trying to get my BG at night to around 140 and 155 during lows during day.

    Type 2 diabetic under control needs to be 140 to 160 A1c 6 to 7.
    - under control.

    I had liver issues - dawn effect at 238 in am and 278 to 311 from liver dumps. My liver/brain always seemed to think Jim needed the french foreign legion glucose death march load of glucose - he is starving - we better ram that up.

    My Doctor twigged that it was critical to prevent glucose going under 100 and cause liver dumps.

    On another note twice as many people die in hospitals when glucose held low to 110 and under rather than 140 to 180,

    My doctor offered they stay longer in hospital and heal slower as well.

    Once I had my glucose down to average 155 - A1C of 6.9; my eye hemorrages healed; kidneys stabalized; and body healed. Take your vitamin supplements.

    Hope these comments provide suggestions for review

    best wishes and luck - I do not want to be in hospital either - nix to that.

    Posted by jim snell |
  17. Apart from cleaning one’s hands for hygiene reasons, which I must admit I often don’t when I’m away from means to do so, using water makes perfect sense rather than using alcohol. Glucose and other sugars are really not very soluble in alcohol (propanol or ethanol) but are freely soluble in water. Although alcohol bought as swabs or from a store as a liquid may contain some water, the alcohol still prevents sugar from dissolving in it freely so is likely to be poor at removing it from the skin. If you can not easily wash your hands then using an alternative site to draw blood could be used, such as the forearm. Besides, alcohol use will tend to harden the skin, making life just that bit more difficult than it need be for us.

    Posted by Steven Dive |
  18. I always wash my hands with soap and water before taking a blood sample.Is that okay? Does it affect the readings?

    Thank you.

    Posted by Ron T. |
  19. Unfortunately a lot of solid and liquid soaps (especially the “soft on hands” varieties) contain sugar. I used to get wildly fluctuating readings (from 5.2 to 8.8) in multiple consecutive tests and found this to be the culprit. Typical of the medical industry to overlook something so basic and obvious.

    Posted by Dying Betic |

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