What has your blood sugar been up to lately? The A1C test—also known as the hemoglobin A1C or HbA1c test—is a simple blood test that measures your average blood sugar levels over the past 3 months. Higher A1C levels are linked to diabetes complications, so reaching and maintaining your individual A1C goal is really important if you have diabetes.
When sugar enters your bloodstream, it attaches to hemoglobin, a protein in your red blood cells. Everybody has some sugar attached to their hemoglobin, but people with higher blood sugar levels have more. The A1C test measures the percentage of your red blood cells that have sugar-coated hemoglobin.
Managing diabetes : If you have diabetes, get an A1C test at least twice a year, more often if your medicine changes or if you have other health conditions. Talk to your doctor about how often is right for you. However, ask your doctor if other tests will be done at the same time and if you need to prepare for them. Since the A1C test reflects your average blood glucose levels over the past 3 months, testing early in pregnancy may include values reflecting time before you were pregnant.
The glucose challenge test or the oral glucose tolerance test OGTT are used to check for gestational diabetes , usually between 24 and 28 weeks of pregnancy. If you had gestational diabetes, you should be tested for diabetes no later than 12 weeks after your baby is born.
If your blood glucose is still high, you may have type 2 diabetes. Even if your blood glucose is normal, you still have a greater chance of developing type 2 diabetes in the future and should get tested every 3 years. For these blood glucose tests used to diagnose diabetes , you must fast at least 8 hours before you have your blood drawn. In some cases, health care professionals use the A1C test to help confirm the results of another blood glucose test.
In some people, a blood glucose test may show diabetes when an A1C test does not. The reverse can also occur—an A1C test may indicate diabetes even though a blood glucose test does not. Because of these differences in test results, health care professionals repeat tests before making a diagnosis. People with differing test results may be in an early stage of the disease, when blood glucose levels have not risen high enough to show up on every test.
In this case, health care professionals may choose to follow the person closely and repeat the test in several months. Lab test results can vary from day to day and from test to test. This can be a result of the following factors:. Your results can vary because of natural changes in your blood glucose level. For example, your blood glucose level moves up and down when you eat or exercise. Sickness and stress also can affect your blood glucose test results. The following chart shows how multiple blood glucose measurements over 4 days compare with an A1C measurement.
The straight black line shows an A1C measurement of 7. The blue line shows an example of how blood glucose test results might look from self-monitoring four times a day over a 4-day period. Conditions that change the life span of red blood cells, such as recent blood loss, sickle cell disease , erythropoietin treatment, hemodialysis , or transfusion, can change A1C levels.
A falsely high A1C result can occur in people who are very low in iron; for example, those with iron-deficiency anemia. Other causes of false A1C results include kidney failure or liver disease.
People in these groups may have a different type of hemoglobin, known as a hemoglobin variant, which can interfere with some A1C tests. However, because you are more likely to check your blood sugar in the morning and before meals, your meter readings will likely be lower than your eAG.
Log in menu Manage Account Search. Donate now. Understanding A1C. Understanding A1C A1C does it all. The big picture: monitoring treatment This relatively simple blood test can tell you a lot. A health care professional will take a blood sample from a vein in your arm, using a small needle.
After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out.
This usually takes less than five minutes. There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly. Your results may mean something different. If you have questions about your results, talk to your health care provider.
Your health care provider may have other recommendations for you, depending on your overall health, age, weight, and other factors. Learn more about laboratory tests, reference ranges, and understanding results. The HbA1c test is not used for gestational diabetes , a type of diabetes that only affects pregnant women, or for diagnosing diabetes in children. Also, if you have anemia or another type of blood disorder , an HbA1c test may be less accurate for diagnosing diabetes.
If you have one of these disorders and are at risk for diabetes, your health care provider may recommend different tests. The information on this site should not be used as a substitute for professional medical care or advice.
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