Since we found the highest plasma insulin and HOMA-IR levels inpatients with T2DM+obesity+CP who were carriers of the C allele of the IRS-1 rs2943640 compared to the patients with only T2DM and patients with T2DM+obesity, this suggests important contribution of CP to IR progression in this cohort of diabetic patients. The gene discussed is IRS1; the disease is obesity due to melanocortin 4 receptor deficiency.