INS and obesity due to melanocortin 4 receptor deficiency: For plasma insulin, groups with diet-induced obesity had significantly higher concentrations (obesity 1: 20.06 (0.68) μU/mL/p < 0.0001, and obesity 2: 21.99 (0.61) μU/mL/p < 0.0001) than those of control 1 (Figure 6B).