Glucose Tolerance Test (GTT/OGTT)

The oral glucose tolerance test (OGTT or GTT) measures how efficiently your body processes sugar by testing blood glucose levels fasting and then at intervals (typically one and two hours) after drinking a standard glucose solution. For women with PCOS, the OGTT is considered the gold-standard screening for insulin resistance and prediabetes because it catches approximately 40% more cases of glucose dysregulation than fasting glucose tests alone—meaning many women with PCOS would appear 'normal' on simpler blood sugar tests while actually having impaired glucose tolerance. Leading PCOS guidelines recommend that all women with PCOS undergo an OGTT at diagnosis and regularly thereafter.