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What to believe?



I every so often use a friends glucometer to check my blood sugar as I have a family Hx of diabetes Type I, maternal grandparent. One day my fasting was about 101 and at the MD office I work for they told me to watch for something called pre-daibetes. So, I got a little paranoid and bought a glucometer. I`ve taken my post meal reading and it never goes above 130 and 2 hours after is in below the 115`s. Same for the random readings. I took a post meal lab test and it was 86, with an A1C of 5.7. I am completely asymptomatic, I run every day and otherwise live a pretty healthy lifestyle.

What is throwing me for a loop is the glucometer. One morning I woke up at 4am and my glucose said 86. Then, at 8 or so am my glucose was 118. Later in the morning, still fasting it was 96. So, yeah the pre-dawn phenomenon. I realize that a glucometer isn`t as accurate as the lab but everything I have read says that the lab would typically read higher than a glucometer. Is the glucometer accurate? It`s new and seems to read similar to my friends glucometer at least when doing random tests.

I`ve read that glucometers can be +- up to 30 pts and that they are most accurate for diabetics to make treatment decisions. Yet, other sites / studies say that they are pretty tight and their readings should be trusted.

I know it makes sense no matter what to continue living a good lifestyle etc etc but what I am looking for is an expert take on glucometers (and the trend of what appears to be a dawn phenom with me and if that is as dangerous as a pre-diabetic condition?)

Thank you so much for your time.


Glucose meters provide a very rough estimate but are not accurate enough to allow diagnoses of diabetes to be established or ruled out.  hence I would not place too much reliance on these results.  In terms of differences between pre- and post-meal glucoses, there is a wide range of normal variation which could explain the findings you describe.  Stick with your basic premise that living a healthy lifestyle has tremendous benefits and don't over-rely upon data which is not accurate enough to answer the questions you want to address.

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Response by:

Robert M Cohen, MD Robert M Cohen, MD
Professor of Clinical Medicine
College of Medicine
University of Cincinnati