A1C is a blood test for type 2 diabetes and prediabetes. It measures your average blood glucose, or blood sugar, level over the past 3 months. Doctors may use the A1C alone or in combination with other diabetes tests to make a diagnosis. They also use the A1C to see how well you are managing your diabetes. This test is different from the blood sugar checks that people with diabetes do every day.
Your A1C test result is given in percentages. The higher the percentage, the higher your blood sugar levels have been:
A normal A1C level is below 5.7 percent
Prediabetes is between 5.7 to 6.4 percent. Having prediabetes is a risk factor for getting type 2 diabetes. People with prediabetes may need retests every year.
Type 2 diabetes is above 6.5 percent
If you have diabetes, you should have the A1C test at least twice a year. The A1C goal for many people with diabetes is below 7. It may be different for you. Ask what your goal should be. If your A1C result is too high, you may need to change your diabetes care plan.
NIH: National Institute of Diabetes and Digestive and Kidney Diseases