Hemoglobin A1c

About the Test

Purpose of the test

The hemoglobin A1c test may have several purposes:

• Screening for prediabetes and diabetes: If you are over 40 and are obese, overweight, or otherwise at high risk for diabetes, your doctor may want to check for health conditions before you experience symptoms. The test can be used for diabetes screening, but the results may need to be confirmed by repeating the test or using another type of test.
• Diagnosing prediabetes and diabetes: This uses tests and procedures to find out the cause of health changes. Your doctor may order hemoglobin A1c and other tests if you have symptoms or show signs of diabetes. Symptoms can include excessive thirst, frequent urination, blurred vision, tingling or loss of sensation in the feet and hands, and feeling extremely tired.
• Monitoring diabetes: If you have been diagnosed with diabetes, your doctor may order this test at least twice a year. This gives your doctor an idea of how well your blood glucose has been controlled in the months between appointments and allows your doctor to make adjustments to your treatment plan and lower your chance of health problems.

The hemoglobin A1c test is not used to diagnose gestational diabetes, a form of the disease that can develop during pregnancy.

What does the test measure?

The hemoglobin A1c test measures the percentage of hemoglobin A in your blood that has glucose attached.

Glucose is the type of sugar that your body uses as its principal energy source. Your body makes or receives glucose from the food you eat. The glucose enters your bloodstream and is taken up by your body’s cells with the help of a hormone called insulin.

If your body isn’t able to make enough insulin, or if your body’s cells have trouble accepting insulin, your blood glucose level can rise to a dangerous level. This may lead to diabetes, a serious disease that can damage your body’s organs if it is not kept under control.

Glucose has the ability to attach to hemoglobin in the blood and form hemoglobin A1c. Hemoglobin is the protein in red blood cells that carries oxygen. Measurement of hemoglobin A1c reflects the percentage of hemoglobin A that is attached to glucose compared to the total amount of hemoglobin A in the blood.

The more glucose in the blood, the more glucose can attach to hemoglobin. If your hemoglobin A1c percentage is too high, your average blood glucose in the previous months has been too high as well.

When should I get this test?

The CDC recommends every adult age 45 and older, or those under 45 who are overweight and have risk factors for prediabetes or type 2 diabetes get a baseline A1c test.

If your result comes back normal, repeat the test every three years. If your results show you have prediabetes, repeat the test as often as your doctor recommends, which is usually every one to two years.

If you have diabetes, it is important to get an A1c test at least once a year and more often if you change your medication or have other health conditions. Your doctor can help determine how often you should get tested.

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