HbA1c is short for glycated hemoglobin, which is a protein in red blood cells that carries oxygen throughout the body. The HbA1c test measures the percentage of hemoglobin in the blood that has glucose attached to it. Glucose in the blood sticks to hemoglobin, and as blood glucose levels increase, more of the hemoglobin will be coated with glucose. Since red blood cells live for about 2-3 months, the HbA1c test shows the average level of glucose in the blood for the past 2-3 months.

The HbA1c test is used to diagnose diabetes and to monitor blood glucose control in people with diabetes. For people without diabetes, the normal range for the HbA1c level is between 4% and 5.6% . HbA1c levels between 5.7% and 6.4% mean that a person has prediabetes and a higher chance of getting diabetes. Levels of 6.5% or higher mean that a person has diabetes.

The HbA1c test is a blood test that is used to screen for or diagnose diabetes and prediabetes. It can also help monitor a persons condition and check how well they have been able to control their blood sugar levels. The Centers for Disease Control (CDC) recommends HbA1c testing for diabetes and prediabetes if a person is over age 45. If a person has diabetes or prediabetes, an HbA1c test can help monitor their condition and check how well they have been able to control their blood sugar levels.