A1C and self-monitoring inconsistent

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Spirit replied on Thu, Nov 5 2009 3:12 PM

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Nelle:  There are a few things to consider:

1). Even meters rated highly accurate have a built in range of error.  Check the literature on your meter to see what this is for your particular meter.  So, each reading you get could actually be higher or lower by several points. 

2). When we test, our meters can only tell us what our glucose reading is for that particular moment in time.  Everyone's glucose levels fluctuate a bit (even non-diabetic's) and you may be missing some readings that are having an impact on your A1c.  For example, in my own case I have found that a meal high in fats gives me my highest reading after the two hour mark, not at it.

3).  The A1c and our home meters do not test exactly the same thing.  Meters tell how how much glucose is in our bloodstream at any given moment; A1c tells us what percentage of our red blood cells have become glycated (sugar-coated) over the course of the average life of a red blood cell which is more or less three months.  Although there is a very strong correlation between these two things, the A1c is not a mathmatical average. 

4). Some people seem to show a bit higher A1c than their daily logs would indicate; some people show a bit lower and some people seem to be right on the money.  There has been some research into this, but as far as I know no defintive answer yet.  It just seems that some people have a tendency to either have more sugar stick or to have less.

5). In any case, even though the exact numbers don't match up perfectly, the information that both testing methods is giving you is the same.  That is, that you are doing an excellent job managing your blood glucose responses.  And THAT'S the important thing to take away from your test results. 

Congratulations on a job well done!

Spirit 

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Ron AKA replied on Thu, Nov 5 2009 3:33 PM

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Have a look at This Thread. I have similar issues. You can find more detail in the Study link that I posted in that thread, but the short story is that the A1C test is inconsistent from person to person. You can have two people with the same average BG readings, but their A1C will be different. This is part of the reason why A1C is not used to diagnose diabetes. BG is the gold standard, and A1C is just a rough estimate of average BG.

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Nelle replied on Thu, Nov 5 2009 3:44 PM

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Thanks to you both. Interesting information.  I have noticed often that my BG is higher at 2 hours after than at 1 hour after.  It could be that the fat is slowly the absorption of the carbs.

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Spirit replied on Thu, Nov 5 2009 3:48 PM

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Yes, fats are the most difficult to digest and they simply slow the rate of digestion. 

Spirit