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A1C test

HbA1C test; Glycated hemoglobin test; Glycohemoglobin test; Hemoglobin A1C; Diabetes - A1C; Diabetic - A1C

A1C is a lab test that shows the average level of blood sugar (glucose) over the previous 3 months. It shows how well you are controlling your blood sugar to help prevent complications from diabetes.

How the Test is Performed

A blood sample is needed. Two methods are available:

  • Blood drawn from a vein. This is done at a lab.
  • Finger stick. This can be done in your health care provider's office. Or, you may be prescribed a kit that you can use at home. Results by finger stick may differ slightly from blood drawn from a vein, but in most cases can also be used to monitor your treatment.

How to Prepare for the Test

No special preparation is needed. The food you have recently eaten does not affect the A1C test, so you do not need to fast to prepare for this blood test.

How the Test will Feel

With a finger stick, you may feel slight pain.

With blood drawn from a vein, you may feel a slight pinch or some stinging when the needle is inserted. Afterward, there may be some throbbing or a slight bruise. This soon goes away.

Why the Test is Performed

Your provider may order this test if you have diabetes. It shows how well you are controlling your diabetes.

The test may also be used to screen for diabetes.

Ask your provider how often you should have your A1C level tested. Usually, testing every 3 or 6 months is recommended.

Normal Results

The following are the results when A1C is being used to diagnose diabetes:

  • Normal (no diabetes): Less than 5.7%
  • Pre-diabetes: 5.7% to 6.4%
  • Diabetes: 6.5% or higher

If you have diabetes, you and your provider will discuss the correct range for you. For many people, the goal is to keep the level below 7%.

The test result may be incorrect in people with anemia, kidney disease, liver disease, or certain blood disorders (thalassemia). Talk to your provider if you have any of these conditions. Certain medicines can also result in a false A1C level.

The examples above are common measurements for results of these tests. Normal value ranges may vary slightly among different laboratories. Talk to your provider about the meaning of your specific test results.

What Abnormal Results Mean

An abnormal result means that you have had a high blood sugar level over a period of weeks to months.

If your A1C is 6.5% or higher and you do not already have diabetes, you may be diagnosed with diabetes.

If your level is above 7% and you have diabetes, it often means that your blood sugar is not as well controlled as would be ideal. You and your provider should determine your target A1C.

Many labs now use the A1C to calculate an estimated average glucose (eAG). This estimate may be different from the average blood sugars you are recording from your glucose meter or continuous glucose monitor. Talk to your provider about what this means. The actual blood sugar readings are usually more reliable than the estimated average glucose based on the A1C.

The higher your A1C, the higher the risk that you will develop problems such as:

If your A1C stays high, talk to your provider about how to best manage your blood sugar.

Risks

There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.

Other risks of having blood drawn are slight, but may include:

  • Excessive bleeding
  • Multiple punctures to locate veins
  • Fainting or feeling lightheaded
  • Hematoma (blood accumulating under the skin)
  • Infection (a slight risk any time the skin is broken)

References

American Diabetes Association Professional Practice Committee; Drazin B, Aroda VR, et al. 6. Glycemic targets: standards of medical care in diabetes - 2022. Diabetes Care. 2022;45(Suppl 1):S83-S96. pubmed.ncbi.nlm.nih.gov/34964868/.

Chernecky CC, Berger BJ. Glycosylated hemoglobin (GHb, glycohemoglobin, glycated hemoglobin, HbA1a, HbA1b, HbA1c) - blood. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. St Louis, MO: Elsevier Saunders; 2013:596-597.

  • HbA1c

    Animation

  •  

    HbA1c - Animation

    If you have diabetes, it's important to keep tight control of your blood sugar. The Hemoglobin A1c test, or HbA1C test, is one way to find out if you are in control. Hemoglobin is an important part of the red blood cell. Red blood cells live about three months. During the life of a red blood cell, sugar molecules, also floating around in your blood, tend to want to stick to the hemoglobin of your red blood cells. Identifying these sugar molecules allows us to get an approximate three-month average of how high persons blood sugars have been. The HbA1c test helps us diagnose a patient suspected of having diabetes and monitors the blood sugar of a diabetic patient. Now, how do we screen for diabetes? If your doctor suspects you have diabetes, your physician will order this simple blood test. A normal HbA1c level is less than 6.0%, which is a three month blood sugar average of around 126 milligrams per deciliter, written like this in your lab results. (126 mg/dl). A HgbA1c level of 5.7 to 6.4% means you are pre-diabetic or borderline-diabetic. If your HgbA1C is 6.5% or higher, you are considered to be a diabetic. That correlates roughly to a 3-month blood sugar average of 140. So, if you are a diabetic, what level should your HbA1c be? Through a combination of a good diabetic diet that controls for carbohydrates, proteins, fats and calories, the American Diabetes Association currently recommends a HbA1C goal of less than 7%. I should also point out that the American Association of Clinical Endocrinologists recommends an even stricter control of diabetes - with a recommended goal of less than 6.5%. What we do know is diabetes causes permanent and irreversible damage to the nerves, blood vessels and body organs, like your eyes, kidneys, heart and also your feet. So, it's critical to get and keep your diabetes under good control to avoid serious long-term health problems. People often ask -- How often should a hemoglobin A1C test be done IF you are a diabetic? Since the HbA1c Test reflects 3 months of control, I recommend getting checked every 3 months to let you, and your doctor know how you're doing. Remember, if you have diabetes, keeping good control of your blood sugar reduces your risk for long-term health problems, like Eye, heart, kidney problems, and even stroke. See your doctor for HbA1c tests every 3 months; you'll be glad you did.

  • Blood test

    Blood test - illustration

    Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. Preparation may vary depending on the specific test.

    Blood test

    illustration

  • HbA1c

    Animation

  •  

    HbA1c - Animation

    If you have diabetes, it's important to keep tight control of your blood sugar. The Hemoglobin A1c test, or HbA1C test, is one way to find out if you are in control. Hemoglobin is an important part of the red blood cell. Red blood cells live about three months. During the life of a red blood cell, sugar molecules, also floating around in your blood, tend to want to stick to the hemoglobin of your red blood cells. Identifying these sugar molecules allows us to get an approximate three-month average of how high persons blood sugars have been. The HbA1c test helps us diagnose a patient suspected of having diabetes and monitors the blood sugar of a diabetic patient. Now, how do we screen for diabetes? If your doctor suspects you have diabetes, your physician will order this simple blood test. A normal HbA1c level is less than 6.0%, which is a three month blood sugar average of around 126 milligrams per deciliter, written like this in your lab results. (126 mg/dl). A HgbA1c level of 5.7 to 6.4% means you are pre-diabetic or borderline-diabetic. If your HgbA1C is 6.5% or higher, you are considered to be a diabetic. That correlates roughly to a 3-month blood sugar average of 140. So, if you are a diabetic, what level should your HbA1c be? Through a combination of a good diabetic diet that controls for carbohydrates, proteins, fats and calories, the American Diabetes Association currently recommends a HbA1C goal of less than 7%. I should also point out that the American Association of Clinical Endocrinologists recommends an even stricter control of diabetes - with a recommended goal of less than 6.5%. What we do know is diabetes causes permanent and irreversible damage to the nerves, blood vessels and body organs, like your eyes, kidneys, heart and also your feet. So, it's critical to get and keep your diabetes under good control to avoid serious long-term health problems. People often ask -- How often should a hemoglobin A1C test be done IF you are a diabetic? Since the HbA1c Test reflects 3 months of control, I recommend getting checked every 3 months to let you, and your doctor know how you're doing. Remember, if you have diabetes, keeping good control of your blood sugar reduces your risk for long-term health problems, like Eye, heart, kidney problems, and even stroke. See your doctor for HbA1c tests every 3 months; you'll be glad you did.

  • Blood test

    Blood test - illustration

    Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. Preparation may vary depending on the specific test.

    Blood test

    illustration

Tests for A1C test

 
 

Review Date: 4/29/2022

Reviewed By: Sandeep K. Dhaliwal, MD, board-certified in Diabetes, Endocrinology, and Metabolism, Springfield, VA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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