Also known as: Glycated Hemoglobin, Hb A1c.

The A1c (Glycohemoglobin) test evaluates the average amount of glucose in the blood over the last two to three months. This is done by measuring the concentration of glycated (also often called glycosylated) hemoglobin A1c. Hemoglobin is an oxygen-transporting protein that is found inside red blood cells (RBCs). The predominant form is hemoglobin A.

In 2010, the American Diabetes Association affirmed the decision of an international expert committee recomendation to use the A1c test to diagnose diabetes with a threshold >/= 6.5%.  Point-of-care A1c assays are not sufficiently accurate at this time for diagnostic purposes.