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)

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 the following:

• Atypical antipsychotics, especially olanzapine
• Corticosteroids
• Diazoxide
• Intravenous dextrose
• Diuretics
• Epinephrine
• Estrogens
• Glucagon
• Isoniazid
• Lithium
• Phenothiazines
• Phenytoin
• Salicylates (acute toxicity -- see aspirin overdose)
• Triamterene
• Tricyclic antidepressants

Drugs that can decrease glucose measurements include the following:

• Acetaminophen
• Alcohol
• Anabolic steroids
• Clofibrate
• Disopyramide
• Gemfibrozil
• Monoamine oxidase inhibitors (MAOIs)
• Pentamidine
• Sulfonylurea medications (such as glipizide, glyburide, and glimepiride)