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What is haemoglobin A1C?

Haemoglobin 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).



A1C level and average blood sugar



If your A1C level is (percent):

That means your average blood sugar level during the past 2 to 3 months was about:

If you live in the US use these values.

Your blood sugar is measured in milligrams/deciliter (mg/dL).

If you live outside the US, use these values.

Your blood sugar is measured in millimoles/liter (mmol/L).































The A1C blood test tells you what your average blood sugar level has been for the past 2 to 3 months. This table lists which A1C levels go with which average blood sugar levels. Blood sugar

is measured differently in the US than it is in most other countries. The column in the middle is for people in the US. The column on the right is for people who live outside the US.



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.