As a result of these beneficial effects of GLP-1R activation on metabolism, several drugs acting on the GLP-1R have been developed for the treatment of T2DM and obesity, including the GLP-1RAs liraglutide and exendin-4 or its synthetic version exenatide, and additional products are in different stages of development (Nauck et al., 2016; Odawara et al., 2016; Oh and Olefsky, 2016; Sheu et al., 2016). Here, GLP1R is linked to type 2 diabetes mellitus.