Overview The A1C test is a common blood test used to diagnose type 1 and type 2 diabetes. If you're living with diabetes, the test is also used to monitor how well you're managing blood sugar levels. The A1C test is also called the glycated hemoglobin, glycosylated hemoglobin, hemoglobin A1C or HbA1c test.

An A1C test measures the average amount of glucose (sugar) in your blood over the past three months. The result is reported as a percentage. The higher the percentage, the higher your blood glucose levels have been, on average. A1C is a simple blood test that healthcare providers use to: Detect prediabetes. Help diagnose Type 2 diabetes.