The Glucose Tolerance Test (GTT) is a diagnostic procedure that evaluates how the body processes glucose after consuming a standardized amount of sugar. This test measures blood glucose levels at fasting and two hours after drinking a glucose solution to assess carbohydrate metabolism and diagnose diabetes mellitus or impaired glucose tolerance. The GTT is particularly valuable for evaluating patients with borderline fasting glucose levels, diagnosing gestational diabetes in pregnant women, and investigating unexplained symptoms that may be related to glucose metabolism disorders. Abnormal results can indicate diabetes, prediabetes, or other conditions affecting glucose regulation such as Cushing's syndrome, pheochromocytoma, or acromegaly. The test requires specific preparation including a high-carbohydrate diet for three days prior to testing and fasting for 8-14 hours before the test to ensure accurate results.