The hemoglobin A1C test, also known as the HbA1C test, provides a long-term indication of blood glucose level. What makes a "good" A1C score depends on whether or not you are diabetic.
The A1C test works by measuring what percentage of hemoglobin in a blood sample shows evidence of contact with blood sugar. Since a red blood cell remains in circulation for about 90 days, the A1C test indicates average blood sugar over the past three months.
Diabetes Maintenance Scores
According to the American Diabetes Association, most people with diabetes should aim to keep their A1C score below 7.0. This score corresponds to an average blood glucose of 154 mg/dl over the past three months.
The A1C test can also be used for diagnosing diabetes. Although A1C scores from 4.0 to 6.0 are considered "normal," a score above 5.7 indicates an increased risk for developing diabetes. A diagnosis of diabetes requires an A1C score of 6.5 or higher.