The A1C test measures a person’s average blood glucose or blood sugar levels over the past 3 months. An A1C reading of over 5.6% may be a cause for concern, but this will depend on various factors.

An A1C test is a blood draw used to diagnose and manage prediabetes and diabetes. Learn more about who needs this test and ...

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 ...