Definition:
A blood glucose test measures the amount of sugar (glucose) in a sample of your blood. See also:
Alternative Names:
Random blood sugar; Blood sugar level; Fasting blood sugar
How the test is performed:
Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The 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:
The test may be done while you are fasting or at random. If you are having a fasting glucose blood test, you should NOT eat or drink for 6 hours before the test. A random 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 your 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:
Your doctor may order this test if you have signs of diabetes. It is also used to monitor patients who have the disease. The carbohydrates you eat 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.
References:
American Diabetes Association. Standards of medical care in diabetes -- 2009. Diabetes Care. 2009;32:S13-S61. Inzucchi SE, Sherwin RS. Type 2 diabetes mellitus. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 248.
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