Plasma insulin and glucose levels were measured hourly, from 8 AM to midnight in normal, obese, juvenile diabetic, and adult diabetic persons with and without obesity. Normal persons showed narrow glucose excursions and sharp postprandial insulin spikes. Obese persons showed three fold increases in fasting and postprandial insulin levels. In obese persons with mild carbohydrate intolerance, postprandial insulin release was delayed. Juvenile diabetics manifested complete insulin lack. Severely diabetic adults still showed definite although reduced postprandial insulin spurts, and the entire plasma insulin profile was still elevated by obesity. From plasma insulin areas and previously established values for metabolic insulin clearance, daily peripheral insulin deliveries were calculated: normal, 31 units; obese persons, 114 units; juvenile diabetics, 4 units; adult diabetics, 14 units; adult, obese diabetics, 46 units. Sixty percent of insulin delivery occurred postprandially in normal and nondiabetic obese persons, but, for frankly diabetic subjects, only 25% was delivered postprandially.