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Diabetes

Can You Help Me Understand My Test Results?

03/12/2008

Question:

I`ve got my glucose test = 129, but A1C = 8.38 My husband had glucose = 179, A1C = 6.68 May you please comment if these looks like true results, or you recomment to repeat tests. Thanks

Answer:

You mention two different tests on two different people and are asking how a seeming contradiction between them can be explained.  The blood glucose simply is a measure of the sugar level in the blood at one particular moment in time.  That value can fluctuate from moment to moment with with much of the fluctuation being explainable by recent food intake, physical activity, stress, illness and some other factors.  The "A1c" is a test which is not a direct measure of blood sugar but rather one that varies very gradually depending on the average blood sugar over a period of weeks to months.  That means that blood sugar and the A1c could be in agreement with each other ( both high, both normal or both low) if the blood sugar varies in the same range over a period of weeks.  However they may not agree with each other, if for example there has been a recent change in blood sugar control.  Examples could include a person who has been doing very well on blood sugar control for months and then develops an illness (like a pneumonia) that throws the blood sugars off for a while; or alternatively a person who was in poor blood sugar control and then suddenly "got religion":  that second person could have good blood sugars today but a poor A1c because of the past poor control.

So, the likeliest possibility is that all the results you gave ARE  correct but it takes some thought to come to the correct interpretation.  In a very small fraction of situations, there are factors that can alter the results of the A1c test besides blood sugar and cause a mix-up (that is actually the area that I do research on) - it is the exception and not the rule.

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Response by:

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