About the Test
A hemoglobin A1c (HbA1c) test measures the amount of blood sugar (glucose) attached to hemoglobin. Hemoglobin is the part of your red blood cells that carries oxygen from your lungs to the rest of your body. An HbA1c test shows what the average amount of glucose attached to hemoglobin has been over the past three months. It's a three-month average because that's typically how long a red blood cell lives. The HbA1c 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 higher your A1C level is, the poorer your blood sugar control and the higher your risk of diabetes complications.
Purpose of the test
The hemoglobin A1c test may have several purposes:
Screening for prediabetes and diabetes. If you are over 40 and are obese or overweight, or if you are otherwise at a high risk for diabetes, your doctor may want to screen you. 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.