INS and obesity disorder: Leptin, a 16 kDa protein secreted by adipocyte and the key cytokine linked with obesity and T2DM (Halaas et al., 1995; Moon et al., 2013), acts as an anorectic hormone that restricts lipid storage and body weight gain (Lee et al., 2002), inhibits ectopic lipid accumulation, attenuates lipotoxicity, and improves insulin sensitivity (Minokoshi et al., 2002).