Considering the short half-life (only 2 min) of endogenous GLP-1 (due to dipeptidyl peptidase 4 (DPP-4) degradation), a range of DPP-4 resistant-GLP-1RA (with extended half-life), most of which are in subcutaneous (sc) rather than oral (po) peptide formulation, have been developed for the treatment of metabolic disorders including T2DM and obesity [77]. Here, GCG is linked to type 2 diabetes mellitus.