A1C Test for Diabetes
What is the A1C test?
The A1C (“A-one-C”) is a blood test that checks your average blood sugar over the past 3 months. Sugar absorbed from the foods you eat and drink goes into your bloodstream. The sugar sticks to the hemoglobin protein, which is the part of red blood cells that carry oxygen to the cells in your body. When sugar sticks to the hemoglobin, it forms hemoglobin A1C. The A1C stays in the blood for the life of the red blood cell, which is 90 to 120 days. This means that the amount of A1C in your blood reflects the average level of your blood sugar over the past 3 months.
Another name for this test is hemoglobin A1C test. It is different from a regular blood sugar or blood glucose test. Daily checks of blood sugar show how well treatment is working throughout the day.
Why is this test done?
There are 3 reasons to check your A1C:
- To diagnose prediabetes (blood sugar that is higher than normal, but not quite high enough to be called diabetes)
- To diagnose diabetes
- To see how well you are controlling your blood sugar if you have been diagnosed with diabetes
If you have diabetes, you should have an A1C test every 3 to 6 months. A1C tests are important because:
- They can check the accuracy of the blood sugar results you get at home.
- They help predict your risk of serious problems from diabetes. A high A1C means that your average blood sugar has been high, and this increases your risk of eye, kidney, heart, blood vessel, and nerve damage problems.
How do I prepare for this test?
Usually no preparation is needed for this test. You don’t need to fast before you have the test and it can be done any time of the day.
Talk to your healthcare provider if you have any questions about the test.
How is the test done?
Having this test will take just a few minutes. A small amount of blood is taken with a prick of the finger or from a vein in your arm with a needle.
At some pharmacies you may be able to buy a device that allows you to test A1C at home. The results of the home test may not be the same as results of tests done at your healthcare provider’s office. Ask your provider if you should check your A1C levels at home.
Ask your healthcare provider when and how you will get the result of your test.
What does the test result mean?
The A1C level rises as your average blood sugar level rises.
- The normal range for a person without diabetes is 4 to 5.6.
- The range for prediabetes (being at risk for developing diabetes) is 5.7 to 6.4.
- Diabetes is diagnosed if your A1C is 6.5 or higher.
- The goal for most nonpregnant adults with diabetes is an A1C below 7.
Talk to your healthcare provider about what your A1C level should be.
A1C results may also be given as the eAG, or estimated average glucose. You can use your A1C results and the chart below to know what your average blood glucose has been.
A1C Estimated Average Glucose (eAG) --------------------------------------------- 6 125 mg/dL 7 154 mg/dL 8 183 mg/dL 9 212 mg/dL 10 240 mg/dL 11 269 mg/dL 12 298 mg/dL ---------------------------------------------
Even though you have the A1C test every few months, you need to keep testing your blood sugar at home as often as your provider recommends. The blood sugar test results help you and your healthcare provider know if you are meeting treatment goals and have stable blood sugar levels.
What if my test result is not normal?
If you have not been diagnosed with diabetes and your test result is above normal, talk with your healthcare provider about whether you have diabetes.
If you have been diagnosed with diabetes and your A1C is high, your diabetes plan may need to be changed or you may need help from your healthcare provider, diabetes educator, or a dietitian to help you follow your plan. Your healthcare provider will talk to you about how to lower your blood sugar.
If your test results are not normal, ask your healthcare provider:
- If you need more tests
- What kind of treatment you might need
- When you need to be tested again
- What lifestyle, diet, or other changes you might need to make