On the basis of this observations, it has been suggested that a direct effect of insulin could partly explain the increased incidence of cancer in conditions of hyperinsulinemia, such as obesity and type 2 diabetes; in fact, higher levels of circulating insulin and C-peptide are associated with increased morbidity and mortality for cancer in the general population [21, 24]. This evidence concerns the gene INS and obesity due to melanocortin 4 receptor deficiency.