The hemoglobin A1c test tells you your average level of blood sugar over the past 2 to 3 months. It’s also called HbA1c, glycated hemoglobin test, and glycohemoglobin.  People who have diabetes need this test regularly to see if their levels are staying within range. It can tell if you need to adjust your diabetes medicines. The A1c test is also used to diagnose diabetes.