May 14, 2007
A1c (Glycohemoglobin, HgbA1c), Hyperglycemia and DKA
Question from Lincoln, Nebraska, USA:
I understand that the A1c correlates to the average blood sugar over the last three months (with more recent readings having a greater impact), but what type of hyperglycemia raises the A1c result the most? Is it transient high readings of greater than 250 mg/dl [13.9 mmol/L] that are corrected quickly or more frequent levels of less than 250 mg/dl [13.9 mmol/L] that persist for several hours?
I ask because my most recent A1c was lower than I had expected at 5.2%. I usually have a fasting sugar below 100 mg/dl [5.6 mmol/L]. My highs can be upwards of 300 mg/dl [16.7 mmol/L], but I correct them quickly and I am rarely high for more than a few hours.
Answer:
That question can be tested mathematically, but I don’t have the immediate answer. In theory, the amount of glucose elevation over time determines the value. If you have just a short amount of time with elevated blood sugars, that would be preferred to smaller incremental changes over a longer time. Realize there are several situations that may provide similar results.
JTL
