Surprisingly, in the non-obese group, the individuals of T/T genotype were characterized by significantly higher concentration of glucose and insulin and higher HOMA-IR values, supporting the theory of association between the genotypic variability of rs4880 and increased susceptibility to obesity due to a decrease in the activity of SOD isozymes, leading to increased susceptibility to oxidative damage in tissues, such as β pancreatic cells and altering the response of these cells to the glycemic status. This evidence concerns the gene INS and obesity due to melanocortin 4 receptor deficiency.