INS and diabetes mellitus: The results demonstrated that serum insulin and leptin levels increased, whereas plasma ghrelin concentration decreased with the increase of body weight and body fat in the DIO4W and DIO8W groups when compared with the controls during the development of type 2 diabetes mellitus model in rats, which was consistent with the results of our previous research on high-fat diets and STZ-induced type 2 diabetes mellitus in rats (Briggs et al. 2010).