Diabetes Health Center
This article is from the WebMD Feature Archive
Beyond Blood Sugar: Testing A1c
What's your A1c? If you have diabetes and you don't know the answer, you should.
"The A1c [or glycated hemoglobin or HbA1c] is critical in the management of both type 1 and type 2 diabetes," says Fran Kaufman, MD, president of the American Diabetes Association. "It's a wonderful test."
Kaufman, who is also division head of endocrinology at the Children's Hospital Los Angeles, is not alone in her glowing assessment of the A1c. "The A1c test has been a revolutionary change in diabetes management," says David E. Goldstein, MD, chair of the NGSP steering committee, the organization that developed standards for A1c testing.
Despite enthusiastic reception by experts, the benefits of A1c testing are still not apparent to everyone. Not enough people with diabetes have their A1c tested regularly and, even when they do, many don't understand the results. In a survey conducted by the American Association of Diabetes Educators, only 24% of people with diabetes knew their A1c levels. Given the severe and life-threatening risks of diabetes -- such as heart disease and stroke -- that number is disturbingly low.
The Significance
Everyone with diabetes is familiar with the standard, fasting blood-glucose test that is used to indicate your current blood sugar levels. The fasting test is the warhorse of diabetes management, and it helps you and your doctor see how your treatment is going.
But while the fasting test remains an important part of diabetes treatment, its weakness is that it is an indication of your glucose level only at the moment you take the test. A fasting blood sugar doesn't tell you anything about your blood-sugar levels the rest of the time.
The hemoglobin A1c test -- usually called the A1c -- fills this gap by testing your blood sugar in a different way. As your body processes blood sugar, small amounts of glucose naturally bond with hemoglobin, a protein in the red blood cells. What's significant is that the amount of glucose that combines with the hemoglobin is directly proportional to the total amount of glucose that is currently in your system.
As a result, the hemoglobin bonded with glucose (glycated hemoglobin, or A1c) can be used as an overall record of glucose levels for as long as the individual red blood cell lives, which is about two to three months. While a fasting test gives you an indication only of current glucose levels, the A1c gives you the big picture of what your average levels are over this whole two to three month period.
The Benefits
Getting a reading of overall blood glucose, instead of relying only on a series of fasting readings, has made a big difference in diabetes management.
Goldstein says that fasting-glucose tests alone were not a very good indicator of how well a person was doing in controlling his or her blood sugars. He says that he and other experts used to be surprised by patients who appeared to have good glycemic control -- based on fasting sugars -- but who would then suddenly develop serious complications.
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