This is the gold-standard Oral Glucose Tolerance Test (OGTT), the definitive way to diagnose diabetes. After a fasting blood draw, you will drink a precisely measured 75-gram glucose solution. We then measure your blood glucose level again at the 2-hour mark. This controlled test shows exactly how your body's insulin responds to a standard sugar load. It is the primary test used to screen for gestational diabetes during pregnancy. This test provides the most accurate, reliable data for a definitive diagnosis.