Fasting ClI was significantly and positively associated with obesity class III (p = 0.001) and grams of fat mass (p = 0.005), insulin sensitivity (both the Matsuda index and MISI) and the disposition index (p < 0.001 for all of them), and it was negatively associated with age (p = 0.001) and puberty (p = 0.001), SBP (p < 0.0001), waist (p = 0.006), HOMA-IR, IGI and the insulin-to-glucose AUC ratio (p < 0.001 for all). The gene discussed is INS; the disease is obesity due to melanocortin 4 receptor deficiency.