August 4, 2006
A1c (Glycohemoglobin, HgbA1c), Diagnosis and Symptoms
Question from Monterey, California, USA:
I had an A1c done at my last physical. It was at the high end of normal, 5.8%. Due to this high level, I asked my physician for a two hour Oral Glucose Tolerance Test (OGGT). My fasting level was 90 mg/dl [5.0 mmol/L] and the two hour level was 104mg/dl [5.8 mmol/L] after the 75 gram drink. My physician has advised that this is completely normal. Is this true? I know that not eating enough carbohydrates can cause a false high result in the OGGT, but is there anything that could cause a false low reading? Why would my A1c be so high? I was under a lot of stress the month preceding the A1c.
Answer:
That’s why the A1c isn’t used to diagnose diabetes. Your OGTT was normal, quite normal in fact. There are attributes of red cells that can give invalid A1c results. I really don’t know why yours was as it was, but the GTT was quite normal. Stay active, fit, and maintain a good weight.
LD
