What is a glucose tolerance test?
A glucose tolerance test is a test that measures the body’s response to glucose (sugar) after a period of fasting and over a certain amount of time after drinking a beverage that contains a measured amount of sugar. The test is given in a lab or doctor’s office in the morning before the person has eaten (usually after an eight hour fast). A first sample of blood is taken from the person at time point 0. Then the person drinks a liquid that contains a measured amount of glucose (sugar). Subsequent blood samples are taken at hours 1, 2, and 3. The object is to see how well the body deals with clearing blood sugar over time. Corresponding insulin levels can be obtained to gauge insulin response to glucose load. The test should be performed as described by WHO (World Health Organization), using a sugar load containing the equivalent of 75 g anhydrous (dry powder) dissolved in water.
