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.
Finding a Hemoglobin A1c Test
How can I get a hemoglobin A1c test?
A hemoglobin A1c test is usually ordered by a doctor. Your doctor may refer you to a lab to have the test performed. Or, if the test is to monitor your diabetes, you may have the test in your doctor’s office. Your doctor may also recommend an at-home version of the test.
Can I take the test at home?
The FDA has approved or cleared a number of over-the-counter hemoglobin A1c test kits that you can use at home. At-home versions of the hemoglobin A1c test may not be as accurate as tests that are performed in a lab. But they offer a convenient alternative to testing in a medical office, which may be useful for some patients.
Your doctor can advise you whether taking the test at home would be right for you and may be able to recommend a specific brand.
How much does the test cost?
The full cost of a hemoglobin A1c test depends on many variables, such as what type of hemoglobin A1c test your doctor orders for you, where the test is performed, whether you have medical insurance, and how much of the cost your insurance provider will cover.
Hemoglobin A1c testing can involve several different charges. These can include fees charged by the laboratory for the technician’s labor and the analysis of your sample, as well as the costs of your visits to your doctor’s office to receive the test or discuss its results.
If your doctor has ordered a hemoglobin A1c test for you, many of these charges will be paid in part or in full by your insurance company. But you may still be responsible for out-of-pocket expenses such as deductibles or copayments. Your doctor or insurance provider can give you more information about the costs that you can expect to pay.
The price of an at-home hemoglobin A1c test device can vary greatly depending on the test kit and manufacturer, the number of tests that come with the kit, and whether the device is covered by your insurance. You may also need to pay for replacement cartridges or other components if you use the device regularly.
Taking a Hemoglobin A1c Test
The hemoglobin A1c test requires a sample of blood. If the test is performed at a lab, the sample is taken through a needle from a vein. And if the test is performed in a doctor’s office or taken at home, a fingerstick is used to obtain the blood sample.
Before the test
You do not need to make any specific preparations before getting your hemoglobin A1c test. But be sure to talk to your doctor about any additional tests that may be conducted during the same visit, since some of those tests may require you to fast or change your diet beforehand or to prepare in other ways.
During the test
For a hemoglobin A1c test that uses a blood sample from a vein, the phlebotomist may start by tying a band at the top of your arm under your shoulder to put pressure on your vein, increasing blood flow. They will clean the skin around your vein using a sterile wipe, then insert a small needle into the vein in the pit of your elbow. Your blood sample will be collected in a tube attached to the needle.
You may notice mild discomfort or stinging when the phlebotomist inserts or removes the needle. Most of the time, your blood draw will take five minutes or less to complete.
If your hemoglobin A1c test uses a fingerstick blood sample, your doctor, nurse, or medical assistant will use a lancet to prick the tip of your finger until a drop of blood appears. You may feel a small amount of pain when your finger is pricked. The blood sample will be mixed with a special substance and then put into a cartridge that is inserted into the testing machine.
For at-home testing, you will collect a blood sample from your finger and process the sample yourself.
After the test
You can generally return to normal activities after the hemoglobin A1c test. If you receive a blood draw, the phlebotomist will put a small bandage over the injection site to make sure any bleeding stops. You may want to leave the bandage on for an hour or more. You may notice some bruising where the needle was inserted.
Fingersticks do not typically cause lasting pain or discomfort. If needed, you can apply a bandage to your fingertip to stop the bleeding.
Hemoglobin A1c Test Results
Receiving test results
If your hemoglobin A1c test was performed in a lab, you will generally receive test results in a few business days. Your results may be available to access online, or they may be sent to you through postal mail or email. Your doctor may call you or reach you by email to talk over your results.
If you have a fingerstick hemoglobin A1c test, your test results will be available in a few minutes. Your doctor may discuss the results right away or may schedule an appointment to go over the results at a later date.
Interpreting test results
Hemoglobin A1c test results are given as percentages. Your test report will also have information on the reference ranges used to interpret your results. Reference ranges are the test result ranges considered normal and the test result ranges that may indicate prediabetes or diabetes.
Doctors use the reference ranges along with your overall health context to interpret the results of your hemoglobin A1c test. Your results will be interpreted differently depending on whether the test is used to diagnose or monitor diabetes that has already been diagnosed.
For diagnostic hemoglobin A1c testing, many expert organizations cite these reference ranges:
- Normal: Under 5.7 percent
- Prediabetes: 5.7 to 6.4 percent
- Diabetes: At or over 6.5 percent
While the hemoglobin A1c test can be used to diagnose diabetes, doctors do not often rely on the results of just one test to make this diagnosis. Your doctor may order a repeat of your hemoglobin A1c test or compare your results with other tests that have been performed. Your doctor may also order additional diagnostic tests, such as other blood glucose tests.
To understand what the results of a diagnostic hemoglobin A1c test mean for you, it’s important to talk about them thoroughly with your doctor. They can address how your hemoglobin A1c results fit into the reference ranges, what follow-up tests might be required, and what next steps to take in managing your health.
If your test results show that you have prediabetes, this means that you could have an increased risk of diabetes in the coming years. Your doctor may advise you to make changes to your diet, exercise routine, and other aspects of your lifestyle that could reduce your chance of developing diabetes or delay the onset of this disease.
If you are given a diagnosis of diabetes, your doctor or another health care provider may give you advice about monitoring and managing the disease over time. Steps to take often include using blood glucose tests at home, repeating hemoglobin A1c tests periodically, and making lifestyle changes. You may also be prescribed medications to help control your blood sugar.
When the test is used to monitor diabetes, you will work with your doctor to establish a target hemoglobin A1c number. This goal will be specific to you and may change during the course of your diabetes care based on factors such as your age, your past success in controlling blood glucose levels, and any diabetic complications you may have. Your doctor will also consider whether you are prone to low blood glucose.