Updated July 24, 2006

H-B-A-1-C
(What It Is and Why It Matters)

by Mark Nakamoto

HbA1c error. Several medical conditions can affect the HbA1c test result, including anemia, sickle cell disease (and sickle cell trait), and chronic kidney disease. Simple lab error is a possibility, too. Because HbA1c results are based on hemoglobin levels, anything that affects hemoglobin or the life of red blood cells can affect the HbA1c result. Shortened life spans of red blood cells, such as can happen in people with most forms of anemia or when recovering from blood loss, can falsely lower one’s HbA1c result because the red blood cells have less time to interact and bind with glucose molecules. Iron-deficiency anemia and some forms of genetic abnormalities of hemoglobin may falsely elevate HbA1c results. High levels of vitamins C and E in the blood may interfere with glycation—falsely lowering results.

In some cases, the testing method may contribute to skewed HbA1c results. Alcoholism, the taking of large quantities of aspirin, chronic use of opiate-containing drugs, high levels of blood triglycerides, uremia (high blood levels of nitrogen-containing wastes such as urea—usually caused by kidney failure), high blood levels of vitamin C, and high levels of bilirubin (a product of hemoglobin destruction) in the blood can falsely elevate HbA1c results, depending on a laboratory’s testing method. If your HbA1c test results don’t seem to match your blood glucose monitoring results, talk to your doctor about why this might be the case.

HbA1c and you
The HbA1c test is another tool that you and your health-care team can use to tighten your blood glucose control and reduce your risk for diabetic complications. Work with your team to determine the best, lowest HbA1c goal for you.

Mark Nakamoto is a former Associate Editor at Diabetes Self-Management.

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