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 Reference fasting blood test Opens New Window 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). Some medicines can cause changes in your test results. Make sure that your doctor knows about any medicines you take and how often you take them.
|By:||Reference Healthwise Staff||Last Revised: Reference August 15, 2012|
|Medical Review:||Reference E. Gregory Thompson, MD - Internal Medicine
Reference Alan C. Dalkin, MD - Endocrinology