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What Is the Hba1c Test?

When diabetics self-test to determine current glucose levels, the result is like a snapshot-one moment in time. While that test result is important information, it's only part of the information needed to monitor how well the disease is being controlled. The hba1c (also called glycolated hemoglobin or a1c) test gives a result that shows how well the disease has been controlled over the previous six to 12 weeks. This helps show how effective the patient's management plan is working.

  1. Why the Hba1c Test Is Important

    • High glucose levels in diabetes invite complications to develop. Heart disease and stroke, kidney disease, eye disease, periodontal disease, foot problems, skin disorders, diabetic neuropathy and nerve problems are among serious complications of diabetes. Monitoring glucose levels by means of both the hba1c test and self-monitoring at home can delay or prevent the onset of serious complications of diabetes.

    How the Test Works

    • Glucose in the bloodstream sticks to hemoglobin, the oxygen-carrying portion of red blood cells. By measuring the amount of glucose adhering to the hemoglobin, the average blood glucose level is determined. The more glucose in the blood, the higher the hba1c test result. Over time, old red blood cells are replaced by new red blood cells, changing the glucose record stored in the hemoglobin. Test results are given as a percentage, with seven percent the typical target goal.

    How the Test is Taken

    • The hba1c test is a blood test. A laboratory technician will draw a small vial of blood using a needle inserted into a blood vessel. Since the hba1c level is not affected by short-term fluctuations in glucose levels-such as from eating a meal-the test can be taken at any time of day, with or without fasting first.

    Limitations

    • The hba1c test does not detect hyperglycemia (spikes in glucose level) or hypoglycemia (drops in glucose level). Excessive alcohol use, high triglycerides and kidney failure can cause falsely elevated hba1c readings. Sickle cell disease, blood loss or thalassemia (a disease that causes underproduction of hemoglobin) can all cause falsely low hba1c readings.

    How Often to Take the Test

    • The target for hba1c results is generally considered to be seven percent or below. The Centers for Disease Control recommends getting an hba1c test every three months if your test results are not hitting the target of seven percent or lower, and twice a year thereafter when test results are hitting the target.

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