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Convert HbA1c to Average Blood Sugar Level

sterling

sterling

Well-Known Member
Messages
161
Location
Centre of England
Type of diabetes
Type 2
Treatment type
Tablets (oral)
Using the diabetes.co.uk calculator my first post diagnosis HbA1c of 6.7% given to me on Friday converts to 9 mmol/l.

Convert HbA1c to Average Blood Sugar Level
http://www.diabetes.co.uk/hba1c-to-bloo ... erter.html

My GP is delighted, but I am not so sure. My many readings on a home meter averaged at 6.77 mmol/l and 9 mmol/l was outside my range except for a few dubious readings.

So why is my HbA1c relatively so poor? I had predicated below 6.0%

I am low-carb and high exercise.
 
It's really hard to compare home readings to HbA1c. There are various different formulas to convert average blood sugar to hbA1c and vice-versa, all based on experimentation with groups etc. The calculation you used always looks optimistic to me. Different people glycate at different rates so get different HbA1cs from different avge. BGs. With your readings, you don't know what was happening to your BGs when you weren't testing, for example, overnight, between meals; you don't know what your peaks were at approx Ihr if you test 2 hours after eating, or indeed if you do peak at one hour according to what you eat. There are just too many anomalies to make conversion practical or accurate. I have found that for me, using a TRUE 24 hour average BG from a mathematical model, then applying a thing called the Nathan formula, I get close. I predicted 5.6% and got 5.7% on last HbA1c. Using the normal method you outlined, applied just to the average of my meter readings, would have predicted 5.1%!
My view is it's best just to use the meter to check what food does to you, make alterations accordingly, and to make sure things aren't changing.
 
Thank you, Grazer, for taking the time to respond to me.

This is actually most helpful. I think that I was expecting to make a somewhat mechanical conversion (still having some regard for the difficulty in averaging results that are not taken evenly throughout the 24-hour cycle). I shall be wary next time about converting meter results into an HbA1C prediction.
 
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