What Is A1c?

Overview

An A1c test is a blood test that checks your average blood sugar level over the past 2 to 3 months. This test also is called a glycohemoglobin test or a hemoglobin A1c test.

The A1c test is one of the tests used to diagnose prediabetes and diabetes. If you have diabetes, this test is done to check how well your diabetes has been managed over the past 2 to 3 months. Your doctor can use this information to adjust your treatment, if needed.

What do the results of an A1c test mean?

The test result is usually given as a percentage. The normal A1c is less than 6.0%. You have a higher risk for diabetes if your A1c is 6.0% to 6.4%. If your level is 6.5% or higher, you have diabetes. ^{footnote 1}

The A1c test result also can be used to find your estimated average glucose, or eAG. Your eAG and A1c show the same thing in two different ways. They both help you learn more about your average blood sugar range over the past 2 to 3 months. A1c is shown as a percentage, while eAG uses the same units (mmol/L) as your glucose meter.

Examples:

• 6.0% A1c = 7.0 mmol/L
• 7.0% A1c = 8.6 mmol/L
• 8.0% A1c = 10.2 mmol/L
• 9.0% A1c = 11.8 mmol/L
• 10.0% A1c = 13.4 mmol/L
• 11.0% A1c = 14.9 mmol/L
• 12.0% A1c = 16.5 mmol/L