A1C test results are reported as a percentage. A higher A1C percentage corresponds to higher average blood sugar levels. Results for a diagnosis are interpreted as follows:
- Below 5.7% is normal.
- 5.7% to 6.4% is diagnosed as prediabetes.
- 6.5% or higher on two separate tests indicates diabetes.
For most adults living with diabetes, an A1C level of less than 7% is a common treatment target. Lower or higher targets may be appropriate for some people.
The target of less than 7% is associated with a lower risk of diabetes-related complications. If your A1C level is above your target, your doctor may recommend an adjustment in your diabetes treatment plan.
A1C and self-monitoring
A part of your treatment plan will include self-monitoring at home with a blood glucose meter or other device. Your health care team will direct you on how often and when you should test your blood sugar.
Your self-monitoring device reports your blood sugar levels in milligrams of sugar per deciliter (mg/dL) or millimoles of sugar per liter (mmol/L). The measurement shows your blood sugar level at the time you do the test. Therefore, there is some variability throughout the day based on eating, exercise, stress and other factors.
Self-monitoring helps you make choices about diet and exercise and daily treatment goals, but it also helps you track whether you are meeting your A1C target. For example, if your A1C target is below 7%, your self-monitoring blood sugar levels should be, on average, below 154 mg/dL (8.6 mmol/L).
A1C test results generally correspond with the following results of blood sugar levels:
||Estimated average blood sugar (glucose) level
||126 mg/dL (7 mmol/L)
||154 mg/dL (8.6 mmol/L)
||183 mg/dL (10.2 mmol/L)
||212 mg/dL (11.8 mmol/L)
||240 mg/dL (13.4 mmol/L)
||269 mg/dL (14.9 mmol/L)
||298 mg/dL (16.5 mmol/L)
Limitations of the A1C test
Some factors may interfere with the accuracy of A1C test results. These include:
- Recent or heavy blood loss
- Recent blood transfusion
- Conditions that result in insufficient red blood cells (anemias)
- Hemoglobin variants
The most common form of the oxygen-transporting hemoglobin protein is called hemoglobin A. The presence of other variants of the protein may result in inaccurate A1C test results. Hemoglobin variants are more common among people of African, Mediterranean or Southeast Asian descent.
If you have a hemoglobin variant, your test may need to be sent to a specialized lab or you may need a different test for diagnosis and monitoring of diabetes.