What is an oral glucose tolerance test?

An oral glucose tolerance test is the main way to test for gestational diabetes, a special type of diabetes that can occur during pregnancy. It is a three-hour test during which your blood glucose levels are checked at timed intervals. Some doctors require you to fast for it, which means you cannot have anything to eat or drink for at least eight hours beforehand.

First, your fasting blood glucose level will be checked. Then, you will need to drink a special (very sugary and sweet) beverage. Your blood sugar levels will be checked one, two and three hours later. If your blood sugar readings are above a certain target number, you may be diagnosed with gestational diabetes.