The HbA1C test is a blood test that reflects the average blood glucose levels over the past 3 months, but not its daily fluctuations. This test is used to detect type 2 and pre-diabetes. It is not recommended for diagnosis of type 2 or gestational diabetes.
HbA1C results are reported as a percentage; the higher the percentage, the higher the blood glucose levels.
A normal HbA1C level is below 5.7 percent.
An HbA1C of 5.7 to 6.4 percent indicates prediabetes. People diagnosed with prediabetes may be retested in 1 year. People with an HbA1C below 5.7 percent may still be at risk for diabetes, depending on the presence of other characteristics that put them at risk, also known as risk factors.
People with an HbA1C above 6.0 percent should be considered at very high risk of developing diabetes. A level of 6.5 percent or above means a person has diabetes.
HbA1C does not require fasting, is diagnostically stable/sound, and does not display value instability during stress or illness.
There are several factors that may interfere with use of HbA1C test for diagnostics.
1. Age. The HbA1C test is restricted to adults. The parameters/levels of this test have been optimized for adults, never identified for children or adolescents.
2. Race. The HbA1C levels may vary with race.
3. Anemia or hemoglobinopathy. Abnormal hemoglobin may interfere with the readings of HbA1C levels. This should be taken into consideration.