Hemoglobin A1C is a blood test used to diagnose and monitor diabetes and prediabetes. The result is an average of your blood sugar levels for the past three months. You do not need to fast for this test.
The A1C test measures the percentage of hemoglobin in your red blood cells that are coated with sugar.
For someone without diabetes, a normal A1C level is below 5.7%. Any A1C level above 5.7% will require additional measurements to determine an accurate diagnosis of prediabetes or diabetes.