Oral glucose tolerance test: indications and limitations.

The oral glucose tolerance test has been used in many clinical situations. From a practical standpoint, however, it has limited applicability. The test should never be done to evaluate reactive hypoglycemia. It can be used in the patient whose fasting plasma glucose level is less than 140 mg/dl but who manifests symptoms compatible with complications of diabetes. Finally, all pregnant patients should undergo testing for gestational diabetes with a 50-g glucose screen at 24 to 28 weeks of pregnancy, and a subsequent glucose tolerance test should be performed if the result of that test is abnormal.