In subjects affected by T2DM and consequently resistant to insulin, it has been showed that blood ghrelin concentration was chronically lower than that observed in healthy subjects even when age, sex, and body mass index (BMI) were adjusted, probably as a direct effect of insulin on ghrelin-producing cells (Poykko et al., 2003; Angelidis et al., 2010; Verhulst and Depoortere, 2012). This evidence concerns the gene GHRL and type 2 diabetes mellitus.