It is therefore clear that currently available GLP-1RAs, mimicking on the peripheral action of GLP-1 (7-36)NH2, not only ignore the yet unknown physiology of GLP-1 (9-36)NH2 or its metabolites, but they also fail to address the tissue specific physiology of GLP-1 (7-36)NH2, while pushing to supra-physiological limits the endocrine GLP-1 receptor axis, likely explaining the reported side-effects and only partial success in the treatment of T2D. Here, GCG is linked to type 2 diabetes mellitus.