IRS1 and obesity due to melanocortin 4 receptor deficiency: In carriers of the A allele of the IRS1 gene (rs2943640) significantly higher level of insulin (by 4.08 times) and HOMA-IR (by 4.81 times) were found in patients with T2DM+obesity+CP vs patients with only T2DM, and also in patients with T2DM+obesity higher level of insulin (by 2.44 times) and HOMA-IR (by 3.20 times) were found vs patients with only T2DM.