C. Ronald Kahn, M.D. President and Director, Joslin Diabetes Center What is the A1c blood test? The hemoglobin A1C test is a measure of what we call long term glucose control. The way this works ...

No, not that number, your A1C. Your A1C measures the amount of sugar in your red blood cells and gives an average of your blood sugar over a three-month period. Why is that important? After all ...

The hemoglobin A1C is a measure of longer-term glucose control – which is important because blood sugar constantly changes from day to day. Specifically, ...