The hemoglobin A1C test is a simple blood screening that can diagnose diabetes and also help manage your condition.
It's been used for decades to diagnose diabetes, but what is a hemoglobin A1C test, really? It's actually simpler than it sounds. Basically, this widely-used blood test measures your average blood sugar level over the last two to three months, which is more useful in diagnosing diabetes than a test that measures your blood sugar at one particular point in time.
If your A1C is 6.5 percent or higher, it's likely that you have diabetes. An A1C level between 5.7 percent and 6.4 percent is typically an indication that you have prediabetes, and a reading below 5.7 percent means you do not have diabetes or prediabetes.
You may see the hemoglobin A1C test referred to by other names including glycated hemoglobin or HbA1c. Once you've been diagnosed, a regular A1C test can help determine how well your treatment plan is working to manage your diabetes.
What is a Hemoglobin A1C Test and How Does It Work?
This test is a simple blood screening that requires no prior fasting or special diet. A blood sample will be collected and sent to a lab for analysis.
Hemoglobin is a protein in red blood cells that can bind to glucose. The higher your blood glucose, the more it binds (or glycates) to hemoglobin. Red blood cells have a lifespan of about three months, so the A1C percentage is a reflection of your average blood sugar levels over the past two to three months.
How Often Should I Be Tested?
The frequency of the test depends on your results, your target blood sugar level, your treatment plan, and your doctor's recommendation. If you're diagnosed with prediabetes, you'll get checked once a year to make sure your blood sugar levels are not climbing.
If you are meeting your treatment goals and your blood sugar is generally in the target range, you'll probably have the A1C test twice a year. If your therapy has changed or you are not meeting your glycemic goals, you may be tested four times per year. For most people with diabetes, the goal is to keep their A1C level below 7 percent.
Does It Work for Everyone?
The hemoglobin A1C test is not necessarily accurate for everyone. Your results may be abnormal if:
- You've experienced heavy or chronic bleeding
- You have iron deficiency or anemia
- You've had a recent blood transfusion
- You have an uncommon type of hemoglobin, also called a hemoglobin variant (most common in people of African, Mediterranean, or Southeast Asian heritage)
- You have sickle cell anemia or thalassemia
- You have liver disease
- You have kidney failure
What Should I Do If My Test Result Is High?
For many people, an A1C test result of 7 percent or higher could mean greater risk of diabetes-related complications like eye disease, peripheral neuropathy, and foot problems. That said, everyone's target range varies based on their unique situation. If your A1C test results are above your target range, you need to reevaluate your diabetes management plan with your physician and consider changes to your exercise routine, diet, or medications.
It may be simple, but the hemoglobin A1C test is an important part of diabetes diagnosis and management. If you think you might have diabetes or prediabetes, talk to your doctor about getting tested.
By Joelle Klein
Mayo Clinic, A1C Test
Lab Tests Online, Hemoglobin A1C
National Institutes of Health, Preventing Diabetes Problems
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Medline Plus, A1C
American Diabetes Association, Glycemic Targets: Standards of Medical Care in Diabetes—2018