FASTING BLOOD SUGAR (FBS): Measures baseline plasma glucose concentrations after an overnight fast to detect impaired fasting glucose, prediabetes, or overt diabetes mellitus.

POSTPRANDIAL BLOOD SUGAR (PPBS): Evaluates plasma glucose levels exactly 2 hours after a standardized meal to measure insulin response and post-meal glucose clearance.

RANDOM BLOOD SUGAR (RBS): Measures circulating blood glucose at any given time regardless of food intake to assess acute hyper- or hypoglycemia.