An A1C test measures the average level of glucose (sugar) in your blood over the past two to three months. It does this by determining the percentage of hemoglobin proteins in your red blood cells that are coated with glucose, also known as glycated hemoglobin
. Because red blood cells live about three months, the test reflects your average blood sugar during that period. The result is reported as a percentage-the higher the percentage, the higher your average blood sugar levels have been. This test is used to diagnose prediabetes and diabetes, and to monitor how well a person with diabetes is managing their blood sugar
. Unlike a single blood sugar test, which shows glucose at one moment, the A1C test provides a broader picture of blood sugar control over time
. It does not require fasting before the test. In summary, the A1C test measures the average blood glucose level over the past 2-3 months by assessing the percentage of glucose-bound hemoglobin in the blood, helping diagnose and manage diabetes and prediabetes
