Glucose test

Alternative names:

blood sugar levels; fasting blood sugar; FBS

What the risks are:

• excessive bleeding
• fainting or feeling lightheaded
• hematoma (blood accumulating under the skin)
• infection (a slight risk any time the skin is broken)
• multiple punctures to locate veins

Special considerations:

Many forms of severe stress (for example, trauma, stroke, heart attack, and surgery) can temporarily increase glucose levels.

Drugs that can increase glucose measurements include tricyclic antidepressants, corticosteroids, diazoxide, IV dextrose, diuretics, epinephrine, estrogens, glucagon, isoniazid, lithium, phenothiazines, phenytoin, salicylates (acute toxicity--see aspirin overdose), and triamterene.

Drugs that can decrease glucose measurements include acetaminophen - oral, alcohol, anabolic steroids, clofibrate, disopyramide, gemfibrozil, monoamine oxidase inhibitors, pentamidine, tolazamide, and tolbutamide.

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.