The A1C test gives a broad picture of your blood sugar levels, because it provides an average of your levels over a 120-day span. The A1C test measures the percentage of glycated hemoglobin in your blood. Glycated hemoglobin is created when molecules of hemoglobin (the oxygen-carrying protein in your blood) attach to molecules of glucose (the sugar in your blood). The more sugar you have in your blood, the higher your percentage of glycated hemoglobin, or HbA1c. Someone who does not have diabetes may typically find that about 5% of their hemoglobin is glycated. People with diabetes that is not well-controlled may find that as much as 25% of their hemoglobin is glycated. If an A1C tests shows that 6.5% of your hemoglobin is glycated, your doctor may diagnose you with diabetes.
The A1C test is one of several tools that doctors can use to make an accurate diagnosis of diabetes and create the best treatment plan for you.
More Answers from Stacy Wiegman, PharmD