Patient education: Hemoglobin A1C tests (The Basics)

What is hemoglobin A1C? — Hemoglobin A1C is a blood test that shows what your average blood sugar level has been for the past 2 to 3 months. Doctors and nurses use this test for 2 reasons:

●To see whether a person has diabetes

●To see whether diabetes treatment is working the right way

Other names for hemoglobin A1C are "glycated hemoglobin," "HbA1C," or just "A1C."

How does my A1C number relate to my blood sugar measurement? — The table shows how your A1C numbers relate to your actual blood sugar level (table 1).

What should my A1C numbers be? — That depends on why you have the test.

●When checking for diabetes – If you had an A1C test to see if you have diabetes, your A1C should be 6 or less.

•If your A1C is 6.5 or higher, it probably means you have diabetes, but you should have the test done again to be sure

•If your A1C is between 5.7 and 6.4, you are at risk for getting diabetes. You should probably start doing things that can help prevent diabetes. For example, you should become more active and lose weight (if you are overweight).

●When checking how treatment is working – If you already know you have diabetes, and you had an A1C test to see how well controlled your blood sugar is, your A1C should probably be 7 or less. If you are older than 65 years, your A1C goal will be higher. But you need to check with your doctor on what your level should be. Not everyone with diabetes is the same. Some people need to aim for different A1C levels than others.

Can I do this test at home? — It is now possible to buy kits to test your A1C at home. But home testing of A1C is not usually necessary.

How often should I have an A1C test? — That depends on whether you have diabetes and what your last A1C test showed.

●If you had an A1C test to check for diabetes and your A1C was less than 5.7 (meaning you do not have diabetes), you should have A1C tests done every 3 years

●If you had an A1C test to check for diabetes and your A1C was between 5.7 and 6.4 (meaning you do not have diabetes but are at risk for it), you should have A1C tests about once a year. Your doctor or nurse will tell you how often to be tested.

●If you do have diabetes and your blood sugar is well controlled, you should have A1C tests every 6 months

●If you have diabetes and you recently changed treatment plans or you are having trouble controlling your blood sugar, you should have A1C tests every 3 months

Why do my A1C numbers matter? — Studies show that keeping A1C numbers close to normal helps keep people from getting:

●Diabetic retinopathy, an eye disease that can cause blindness

●Nerve damage caused by diabetes (also called "neuropathy")

●Kidney disease

For people with newly diagnosed diabetes, keeping the A1C close to normal might also prevent heart attacks and strokes in the future.

Do I still need to measure my blood sugar at home? — If your doctor wants you to check your blood sugar at home, you should keep doing so even if you have routine A1C tests. Blood sugar tests tell you what your blood sugar is from moment to moment. That's important information to have, because it lets you know if your medicines and lifestyle changes are keeping your blood sugar in a safe range.

More on this topic

Patient education: The ABCs of diabetes (The Basics)
Patient education: Type 1 diabetes (The Basics)
Patient education: Type 2 diabetes (The Basics)
Patient education: Treatment for type 2 diabetes (The Basics)
Patient education: Using insulin (The Basics)
Patient education: Diabetic retinopathy (The Basics)
Patient education: Nerve damage caused by diabetes (The Basics)
Patient education: Chronic kidney disease (The Basics)
Patient education: Controlling blood sugar in children with diabetes (The Basics)
Patient education: Checking your child's blood sugar level (The Basics)

Patient education: Type 1 diabetes: Overview (Beyond the Basics)
Patient education: Type 2 diabetes: Overview (Beyond the Basics)