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 raise blood glucose levels.

Drugs that can increase glucose measurements include the following:

• Atypical antipsychotic medications, especially olanzapine, quetiapine, and risperidone
• Beta-blockers (such as propranolol)
• Corticosteroids
• Dextrose
• Epinephrine
• Estrogens
• Glucagon
• Isoniazid
• Lithium
• Oral contraceptives (birth control pills)
• Phenothiazines
• Phenytoin
• Salicylates (see aspirin overdose)
• Thiazide diuretics
• 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)