HbA1c (also known as hemoglobin A1c or glycated hemoglobin) is a blood test that measures the average blood glucose level over the past two to three months. It is used to monitor the effectiveness of treatment in people with diabetes and to diagnose diabetes or pre-diabetes.
In people with diabetes, high blood glucose levels can cause glucose to bind to hemoglobin (the protein in red blood cells that carries oxygen), forming HbA1c. The higher the level of glucose in the blood, the higher the level of HbA1c. The test measures the percentage of hemoglobin that is glycated.
The HbA1c test is usually performed once every three to six months and does not require fasting. A normal HbA1c level is less than 5.7 percent. An HbA1c level of 6.5 percent or higher on two separate tests indicates diabetes, while an HbA1c level between 5.7 and 6.4 percent indicates pre-diabetes.
It’s important to note that the HbA1c test may not be accurate in certain conditions, such as anemia, certain types of hemoglobin disorders, or a recent blood transfusion. In these cases, the test may produce false results and should be repeated after the underlying condition has been treated.