Glycosylated Hemoglobin

There is hemoglobin in all red blood cells. Hemoglobin is the part of the red blood cell that carries oxygen to the tissues and organs in the body. Hemoglobin combines with blood glucose to make glycosylated hemoglobin or hemoglobin A1c.

Red blood cells store glycosylated hemoglobin slowly over their 120-day life span. When you have high levels of glucose in your blood, your red blood cells store large amounts of glycosylated hemoglobin. When you have normal or near normal levels, your red blood cells store normal or near normal amounts of glycosylated hemoglobin. So, when you measure your glycosylated hemoglobin, you can find out your level of blood glucose, averaged over the last few months.

Doctors have used the glycosylated hemoglobin test for patients with diabetes since 1976 (1,2). The test is now widely used in the routine monitoring of patients with diabetes mellitus. Your doctor may use this test to see how well you respond to treatment. If you have low test values you probably have lowered risk for having complications from diabetes mellitus.

It is good to have your glycosylated hemoglobin tested at least two times a year if you meet your treatment goals or up to four times a year if you change therapy or do not meet your treatment goals. There are now many different ways to measure glycosylated hemoglobin. These tests vary in cost and convenience and you can do some at home. The values (glycosylated hemoglobin index) these tests give can vary too. Talk to your doctor about what your glycosylated hemoglobin index should be.

Patients with diseases affecting hemoglobin, such as anemia, may get wrong values with this test. Vitamins C and E, high levels of lipids, and diseases of the liver and kidneys may all cause the test results to be wrong.