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Glucose test

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Definition:

A glucose test measures the amount of sugar (glucose) in the blood.

Alternative Names:

FBS; Blood sugar levels; Fasting blood sugar

How the test is performed:

Blood is drawn from a vein ( venipuncture ), usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) 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 (fill with blood).

A needle is inserted into the vein, and the blood is collected in an airtight 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 .

Infant or young child:

The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small 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.

How to prepare for the test:

You should not eat for 6 hours before the test. A random serum glucose test can be done at any time of the day, but results depend on what you drink or eat before the test, as well as activity.

How the test will feel:

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.

Why the test is performed:

This test is used to evaluate blood glucose levels. It may be used to diagnose or screen for diabetes and to monitor control in patients who have diabetes.

Most dietary carbohydrates eventually end up as glucose in the blood. Glucose is a major source of energy for most cells of the body, including those in the brain.

• Review Date: 2/8/2007
• Reviewed By: Robert Hurd, MD, Professor of Endocrinology, Department of Biology, Xavier University, Cincinnati, OH. Review provided by VeriMed Healthcare Network.

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