Diabetes Over View

Glycosylated Heamoglobin Test

Introduction

Diabetics need to monitor blood in order to know their risk of diabetes, hence monitoring the blood is very important. But monitoring blood sugar levels gives the reading of what the blood sugar is at the moment of taking the reading. If these blood sugar levels are monitored two times with a four-hour gap in-between then you have the starting and ending point for the blood sugar levels and what took place between these readings is not known. A medical professional can fill up these gaps using a test called the Hemoglobin A1c test.

Glycosylated hemoglobin A1c, also known as Hb A1c; Hemoglobin - glycosylated; GHb; Glycohemoglobin; Diabetic control index is a reading that reveals the average blood glucose level over the past three months and also it can be used to predict the risk of diabetes complications.

This is a very useful blood test, done by the laboratory, to see how you have been doing overall with respect to the blood sugars. Hemoglobin is a protein that stays in the blood for about 90 days and is easily measured.

Human body actually keeps in memory the track of sugar levels in the body. The sugar molecules attach themselves to red blood cells, which store the sugar information for about 4 months. A blood test can then retrieve your average blood glucose results in the format of a percentage. The greater your A1c value, the higher your risk for diabetes complications.

The glucose in your blood can attach chemically to any proteins present, and stay attached permanently. The amount that attaches to the protein depends on how high the blood glucose is. The glucose stays attached until the body breaks down the hemoglobin molecule naturally. The amount of hemoglobin with glucose attached to it is measured and compared with the total amount of hemoglobin present. This indicates how high the blood glucose has been, at some time in the life of the hemoglobin. For instance, if your glucose was high one month ago, then more glucose would have attached to the hemoglobin molecule at that time, and this could still be measured now.

How is that done?

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 antiseptic, and a tourniquet or blood pressure cuff is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to distend. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. 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 the area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.

This is not such a painful test, when the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Measuring the HgbA1c is a convenient way for your doctor to get more information about your glucose control, and to track your progress. It becomes easy to say, based on these results, whether overall glucose control is actually improving, or worsening. Excellent levels, for someone with diabetes, would be 7.0% (.070) or less of total hemoglobin having glucose attached. When your HgbA1c is good, you can be sure that your glucose levels have been good for a long time.

Preparing for the test

These is no need of fasting before going for the test.

For infants and children the physical and psychological preparation you can provide for this or any test or procedure depends on your child’s age, interests, previous experience, and level of trust.

Risks

This test might result in excessive bleeding, fainting or feeling lightheaded, hematoma (blood accumulating under the skin), infection (a slight risk any time the skin is broken) or multiple punctures to locate veins.

Glycosylated hemoglobin that is 2.2 to 4.8% of total Hb is normal, although normal ranges may vary slightly depending on the laboratory used.

Abnormal outcomes

There might be an inadequate regulation of blood glucose levels over a period of weeks to months. Higher values mean the patient is at higher risk of diabetic complications. Lower values decrease the risk.

This test should be obtained by your doctor every 3 to 6 months to see how well controlled your diabetes is. In general, a value less than 4.5% is ideal. A value greater than 6.1% should prompt a change in your diabetes regimen. These targets may be increased somwhat if you have frequent episodes of low blood sugars (hypoglycemia).

Daily blood glucose testing and HBA1c

Knowing where your blood glucose is every day is still the easiest and most practical way to see how food, exercise and daily living are impacting diabetes. But by comparing your daily blood glucose test results to A1c, you and your doctor can determine how well your diabetes is being controlled and establish ways to control it even further.