Blood Glucose

2-hour Postprandial Blood Sugar Test, Fasting Blood Sugar Test, Random Blood Sugar Test

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

• Eating or drinking less than 8 hours before a fasting blood test or less than 2 hours before a 2-hour postprandial test.
• Drinking alcohol.
• Illness or emotional stress, smoking, and caffeine.

Taking a medicine, such as birth control pills, medicines used to treat high blood pressure, phenytoin (Dilantin), furosemide (Lasix), triamterene (Dyrenium, Dyazide), hydrochlorothiazide (Esidrix, Oretic), niacin, propranolol (Inderal), or corticosteroids (prednisone), can cause changes in your test results. Make sure that your doctor knows about any medicines you take and how often you take them.

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Author:	Christine Wendt, R.D., L.D.	Last Updated: July 14, 2009
Medical Review:	Caroline S. Rhoads, MD - Internal Medicine David C.W. Lau, MD, PhD, FRCPC - Endocrinology & Metabolism
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