The A1C test is a common blood test used to diagnose type 1 and type 2 diabetes. If you live with diabetes, the test is also used to monitor how well you are controlling your blood sugar levels. the a1c test is also called glycated hemoglobin, glycosylated hemoglobin, hemoglobin a1c, or hba1c test.
an a1c test result reflects your average blood sugar level over the past two to three months. Specifically, the A1C test measures what percentage of the hemoglobin proteins in your blood that are sugar-coated (glycated). hemoglobin proteins in red blood cells carry oxygen.
The higher your A1C level, the worse your blood sugar control and the higher your risk of diabetes complications.
why is it done
The results of an A1C test can help your doctor or other health care provider:
- diagnose prediabetes. if you have prediabetes, you are at increased risk of developing diabetes and cardiovascular disease.
- diagnose type 1 and type 2 diabetes. To confirm a diagnosis of diabetes, your doctor will likely look at the results of two blood tests done on different days, either two a1c tests or the a1c test plus another test, such as a random or fasting blood sugar test.
- Monitor your diabetes treatment plan. The result of an initial a1c test also helps establish your a1c reference level. then the test is repeated regularly to monitor your diabetes treatment plan.
- once a year if you have prediabetes
- twice a year if you don’t use insulin and your blood sugar is consistently within your target range
- four times a year if you take insulin or have trouble keeping your blood sugar in your target range
- Below 5.7% is normal.
- between 5.7% and 6.4% are diagnosed as prediabetes.
- 6.5% or more on two separate tests indicates diabetes.
- recent or heavy blood loss
- recent blood transfusion
- conditions that result in insufficient red blood cells (anemias)
- hemoglobin variants
How often you need your A1C test depends on your type of diabetes, your treatment plan, how well you are meeting your treatment goals, and the clinical judgment of your primary care physician. for example, the a1c test may be recommended:
You may need more frequent A1C tests if your doctor changes your diabetes treatment plan or if you start a new diabetes medication.
how do you prepare
The A1C test is a simple blood test. You don’t need to fast for the A1C test, so you can eat and drink normally before the test.
what you can expect
During the A1C test, a member of your health care team takes a blood sample by inserting a needle into a vein in your arm or by pricking the tip of your finger with a small, sharp lancet. if the blood is drawn from a vein, the blood sample is sent to a laboratory for testing.
Blood from a finger prick can be tested at your doctor’s office for same-day results. this in-office test is only used to monitor your treatment plan, not for diagnosis or screening.
a1c test results are reported as a percentage. A higher A1C percentage corresponds to higher average blood sugar levels. the results of a diagnostic are interpreted as follows:
For most adults living with diabetes, an A1C level of less than 7% is a common treatment goal. lower or higher goals may be appropriate for some people.
The goal of less than 7% is associated with a lower risk of diabetes-related complications. If your A1C level is above your goal, your doctor may recommend an adjustment to your diabetes treatment plan.
a1c and self-monitoring
A part of your treatment plan will include self-monitoring at home with a blood glucose meter or other device. Your health care team will tell you how often and when to check your blood sugar.
Your self-monitoring device reports your blood sugar levels in milligrams of sugar per deciliter (mg/dl) or millimoles of sugar per liter (mmol/l). the measurement shows your blood sugar level at the time you test. therefore, there is some variability throughout the day based on diet, exercise, stress, and other factors.
self-monitoring helps you make decisions about diet and exercise and daily treatment goals, but it also helps you monitor whether you’re reaching your a1c goal. For example, if your A1C target is below 7%, your self-monitoring blood sugar levels should be, on average, below 154 mg/dL (8.6 mmol/L).
A1C test results generally correspond to the following blood sugar results:
limitations of the a1c test
Some factors can interfere with the accuracy of your A1C test results. these include:
The most common form of the oxygen-carrying hemoglobin protein is called hemoglobin a. the presence of other variants of the protein can lead to inaccurate a1c test results. hemoglobin variants are more common among people of African, Mediterranean, or Southeast Asian descent.
If you have a hemoglobin variant, you may need to send your test to a specialized laboratory or you may need a different test for diabetes diagnosis and management.