GCG and type 2 diabetes mellitus: The active forms of GLP-1 (7-36 amide and 7-37) are rapidly degraded by dipeptidyl peptidase-4 (DPP-4), and efferent signals contribute to the effects exerted by the native peptide [9], while stable GLP-1 analogs and DPP-4 inhibitors are used in T2D therapy.