GCG and diabetes mellitus: The insulinotropic effect of GLP-1 on the pancreas has been demonstrated to be preserved in animal models of diabetes by stimulating insulin exocytosis (Shen et al., 1998; Drucker, 2001; MacDonald et al., 2002), and promoting insulin biosynthesis (Fehmann and Habener, 1992; Perfetti and Merkel, 2000; Moon et al., 2011).