Does drinking water or doing moderate exercise during the three-hour glucose tolerance test for pregnant women affect the results?

Drinking water should not affect the results. Probably moderate activity (walking around) will not affect the results either, but strenuous activity might.

OWJ
Additional comments from Dr. David Schwartz:

There are specific, but thankfully few, indications to undergo a glucose tolerance test these days. Perhaps the most often used in during pregnancy. The protocol is often adjusted for pregnant women compared to the rest of the world.

Classically, the test is done after the individual has consumed a diet that is rich in carbs (at least 60% of calories) for the preceding 3 days. The patient is fasting after midnight and interfering medications should be avoided that morning. Then the dose of glucose is carefully measured, based on body weight (1.75 gm/kg body weight to a maximum of 75 grams) taken by mouth. Then glucose and insulin levels are measured at the designated times (usually at baseline and at 30, 60, 90, 120, 180, 240 minutes). Some centers will measure urine during the times as well. Patients are advised to remain fasting and relatively inactive during the test.

DS