GLP1R and obesity due to melanocortin 4 receptor deficiency: In addition to the effects of GLP-1 in healthy individuals, several studies (Deane et al., 2010; Meier et al., 2003; Näslund et al., 1998) have shown that exogenous GLP-1 inhibits gastric emptying in patients with T2DM, obesity, and critical illness.