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 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.
Why it’s done
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.
How often you need the A1C test depends on the type of diabetes, your treatment plan, how well you’re meeting treatment goals and your primary care doctor’s clinical judgment. For example, the A1C test may be recommended:
- Once every year if you have prediabetes
- Twice a year if you don’t use insulin and your blood sugar level is consistently within your target range
- Four times a year if you take insulin or have trouble keeping your blood sugar level within your target range
You may need more-frequent A1C tests if your doctor changes your diabetes treatment plan or you begin taking a new diabetes medication.
