IRS1 and obesity due to melanocortin 4 receptor deficiency: In carriers of the C allele of the IRS1 gene (rs2943640) - patients with T2DM+obesity+CP maximum insulin level and HOMA-IR were found, which significantly differed from the data of patients with only T2DM (respectively by 329.75 % and 65.13 %) and from the data of patients with T2DM+obesity (respectively by 314.53 % and 69.23 %) (Table 5).