glucose tolerance test (GTT), a test of the body’s ability to metabolize carbohydrates by administering a standard dose of glucose and measuring the blood and urine for glucose level at regular intervals thereafter. The patient usually eats a high-carbohydrate diet for the 3 days before the test and fasts the night before. A fasting blood glucose level is obtained the next morning, and then the patient drinks a dose of glucose based on his or her weight. Blood and urine are collected periodically for up to 6 hours. The glucose tolerance test is most often used to assist in the diagnosis of diabetes, hypoglycemia, or other disorders that affect carbohydrate metabolism.
