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What is a Hemoglobin A1C Test?

The results can give you a picture of how well your blood sugar is controlled.

male patient talking to his doctor

Whether or not you take insulin every day, it’s important to check how well your diabetes is controlled. Knowing your A1C can help. The A1C test shows what your average blood glucose (sugar) level has been over the past two to three months. It’s a simple blood test that rounds out the daily ups and downs to show you and your doctor how well your diabetes treatment plan has been working.

What is hemoglobin A1C and why is it important?

Hemoglobin is a protein in your red blood cells. It carries oxygen from the lungs to the cells. When your blood sugar is high, more sugar attaches to the hemoglobin. The A1C test measures the amount of sugar that has attached to the hemoglobin.

A higher A1C reading means your blood sugar levels have been high. A lower A1C reading suggests your blood sugar levels are likely under control.

What is a good A1C reading?

Hemoglobin A1C is measured in percentages. Your doctor may set your goal between 6 and 8, based on your age, health, risk of hypoglycemia and your personal situation.

Your doctor should test your A1C. This way, he or she can discuss the results with you and adjust your medication, if necessary.

How often do I need this test?

If your diabetes is controlled and you’re at your target A1C level, your A1C should be tested at least twice a year. If you’re not at your target A1C level, your doctor may want to test your A1C every three months.

If you’re taking insulin, the A1C test should be done in addition to regular home blood sugar monitoring. It may be helpful to think about blood sugar testing like checking your watch and A1C like looking at your calendar.

By Jenilee Matz, MPH, Contributing Writer


American Diabetes Association. Standards of medical care in diabetes 2019. Diabetes Care. Accessed July 30, 2019.
Centers for Disease Control and Prevention. Accessed July 30, 2019.
National Institute of Diabetes and Digestive and Kidney Diseases. Accessed July 30, 2019.

Updated July 30, 2019