We used a 3-hour OGTT with frequent blood sampling to evaluate the effects of obesity and insulin resistance on insulin kinetics in lean people and people with obesity, who were separated into 4 distinct groups on the basis of clinical categories of glycemic control, namely Ob-NFG-NGT, Ob-NFG-IGT, Ob-IFG-IGT, and Ob-T2D. The gene discussed is INS; the disease is obesity due to melanocortin 4 receptor deficiency.