HbA1c also called Glycated hemoglobin gives the average sugar level in the body over a period of 2 to 3 months unlike blood sugar which indicates daily level. This test is used to diagnose prediabetes, diagnose type 1 and type 2 diabetes & monitor your diabetes treatment plan. Initial A1C test also helps to establish your baseline level. How often you need this test depends on the type of diabetes, your treatment plan, how well you are meeting treatment goals and your doctor's clinical judgment. The recommended protocol for this test is: Once every year if you have prediabetes; Twice a year if you do not use insulin and your blood sugar level is consistently within your target range; Four times a year if you take insulin or have trouble keeping your blood sugar level within your target range.