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
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
, 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.