HbA1c

Answer 1

Definition

HbA1c is a test that measures the amount of glycated hemoglobin in your blood. Glycated hemoglobin is a substance in red blood cells that is formed when blood sugar (glucose) attaches to hemoglobin.

Alternative Names

Glycated hemoglobin; Glycosylated hemoglobin; Hemoglobin - glycosylated; A1C; GHb; Glycohemoglobin; Diabetic control index

How the test is performed

Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.

How to prepare for the test

No special preparation is necessary.

How the test will feel

When the needle is inserted to draw blood, you may feel moderate pain, or only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed

Your doctor may order this test if you have Diabetes. It is used to measure your blood sugar control over several months. It can give a good estimate of how well you have managed your diabetes over the last 2 or 3 months.

The test may also be used to screen for diabetes.

You have more glycated hemoglobin if you have had high levels of glucose in your blood. In general, the higher your HbA1c, the higher the risk that you will develop problems such as:

• Eye disease
• Heart disease
• Kidney disease
• Nerve damage
• Stroke

This is especially true if your HbA1c remains high for a long period of time.

The closer your HbA1c is to normal, the less risk you have for these complications.

Normal Values

An HbA1c of 6% or less is normal. A HbA1c above 6.5% is a newly recommended criterion for diagnosing diabetes.

If you have diabetes, you should try to keep your HbA1c level at or below 7%. However, you and your health care provider must decide what is a normal HbA1c level for you.

Normal ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

What abnormal results mean

Abnormal results mean that your blood glucose levels have been above normal over a period of weeks to months. If your HbA1c is above 7%, it means that your diabetes control may not be as good as it should be.

High values mean you are at greater risk of diabetes complications. If you can bring your level down, you decrease your chances of long-term complications.

Ask your doctor how often you should have your HbA1c tested. Usually, doctors recommend testing every 3 or 6 months.

What the risks are

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

• Excessive bleeding
• Fainting or feeling light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

References

International Expert Committee Report on the Role of the A1C Assay in the Diagnosis of Diabetes. Diabetes Care. July 2009 32:1344-1345.

American Diabetes Association. Standards of medical care in diabetes--2010. Diabetes Care. 2010 Jan;33 Suppl 1:S11-61.

Answer 2

Definition

HbA1c is a lab test that shows the average amount of sugar in your blood over 3 months. It shows how well you are controlling your diabetes.

Alternative Names

Glycated hemoglobin; Glycosylated hemoglobin; Hemoglobin - glycosylated; A1C; GHb; Glycohemoglobin; Diabetic control index

How the test is performed

A blood sample is needed. For information on how this is done, see: Venipuncture.

How to prepare for the test

No special preparation is needed.

How the test will feel

When the needle is inserted, you may feel a slight pinch or some stinging. Afterward, there may be some throbbing.

Why the test is performed

Your doctor 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.

Normal Values

An HbA1c of 6% or less is normal.

The following are the results when the HbA1c is being used to diagnose diabetes:

• Normal: Less than 5.7%
• Pre-diabetes: 5.7% to 6.4%
• Diabetes: 6.5% or higher

If you have diabetes, try to keep your level at or below 7%. You and your health care provider must decide what a normal level is for you.

Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.

What abnormal results mean

Abnormal results mean that you have had high blood sugar levels over a period of weeks to months.

If your HbA1c is above 6.5% and you do not already have diabetes, you may be diagnosed with diabetes.

If your level is above 7% and you have diabetes, it means that your diabetes control may not be as good as it should be.

In general, the higher your HbA1c, the higher the risk that you will develop problems such as:

• Eye disease
• Heart disease
• Kidney disease
• Nerve damage
• Stroke

If your HbA1c stays high for a long period of time, the risk for these problems is even greater.

Ask your doctor how often you should have your level tested. Usually, doctors recommend testing every 3 or 6 months.

What the risks are

Obtaining a blood sample from some people may be more difficult than from others.

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

• Excessive bleeding
• Fainting or feeling light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

References

American Diabetes Association. Standards of medical care in diabetes--2011. Diabetes Care. 2011 Jan;34 Suppl 1:S11-61.

Reviewed By

Review Date: 06/28/2011

Ari S. Eckman, MD, Chief, Division of Endocrinology, Diabetes and Metabolism, Trinitas Regional Medical Center, Elizabeth, NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Answer 3

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% - 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.

Reviewed By

Review Date: 10/25/2011

Alan Greene, MD, Author and Practicing Pediatrician; also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Answer 4

HbA1c, or glycated hemoglobin, is a marker used to measure average blood sugar levels over the past 2-3 months. It is commonly used in the management of diabetes to assess long-term blood sugar control. The higher the HbA1c level, the poorer the blood sugar control and increased risk of diabetes complications.