The A1C test measures a diabetic person's blood sugar levels for the previous three months to give an overall view of how under control glucose levels are. The test is also referred to as the HbA1C and it differs from daily glucose monitoring that diabetics do themselves as daily glucose testing is designed to check what the blood sugar level is only for that moment of testing. By using the A1C test to measure a patient's blood sugar averages for the past few months, a doctor can get a better idea of how well diabetes treatments are working to help lower glucose in the blood.
Diabetics must keep blood glucose levels under control to prevent the risk of complications of diabetes such as damage to blood vessels, nerves, eyes and kidneys. Daily monitoring of blood sugar levels is crucial for diabetics, but so is the A1C test. The A1C test is designed to average blood sugars over a period of a few months as that is how long a red blood cell lives in the body. The way that the A1C test works to average blood sugars over the span of a few months is to measure the percentage of glycated hemoglobin, or A1C, or excess sugar that connects with the hemoglobin inside red blood cells. The higher the diabetic's amount of excess glucose, the higher the percentage of A1C present in the body.
Old blood cells are replaced by new blood cells in the body after 120 days, so the A1C is designed to measure glucose levels every three months. Many medical professionals recommend that diabetics get an A1C test a minimum of twice a year — more if the results of a previous test show poor control. The high end of the A1C test is considered to be a blood glucose measurement of 25%, while 5% is considered a normal blood glucose level. Non-diabetics given the A1C test should test at about 5%. The percentage is the measurement of glycated hemoglobin in the body.
A percentage under 7% is considered good blood glucose control for most diabetics. However, the goal is usually 6% for pregnant women and ideally that number should be reached before a diabetic woman conceives. Keeping blood sugar levels at a consistently lower level can help reduce or avoid complications from diabetes that include kidney disease, eye disease and nerve damage.