What is A1C?

The A1C test

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 result reflects your average blood sugar level for the past two to three months. Specifically, the A1C test measures what percentage of hemoglobin proteins in your blood are coated with sugar (glycated). Hemoglobin proteins in red blood cells transport oxygen.

The higher your A1C level is, the poorer your blood sugar control and the higher your risk of diabetes complications. The results of an A1C test can help your doctor or other health care provider:

  • Diagnose prediabetes. If you have prediabetes, you have a higher risk of developing diabetes and cardiovascular disease.
  • Diagnose type 1 and type 2 diabetes. To confirm a diabetes diagnosis, your doctor will likely look at the results of two blood tests given on different days — either two A1C tests or the A1C test plus another test, such as a fasting or random blood sugar test.
  • Monitor your diabetes treatment plan. The result of an initial A1C test also helps establish your baseline A1C level. The test is then repeated regularly to monitor your diabetes treatment plan.
 

What the results mean

A1C test results are reported as a percentage. A higher A1C percentage corresponds to higher average blood sugar levels. Results for a diagnosis are interpreted as follows:

  • Below 5.7% is normal.
  • 5.7% to 6.4% is diagnosed as prediabetes.
  • 6.5% or higher on two separate tests indicates diabetes.

For most adults living with diabetes, an A1C level of less than 7% is a common treatment target. Lower or higher targets may be appropriate for some people.

The target of less than 7% is associated with a lower risk of diabetes-related complications. If your A1C level is above your target, your doctor may recommend an adjustment in your diabetes treatment plan.

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