Although half-life of endogenous GLP-1 is less than 2 min in the blood-stream (Kieffer et al., 1995) because of its cleavage by dipeptidyl peptidase-4 (DPP-4), recent works have demonstrated that various GLP-1 analogs widely used for treatment of type 2 diabetes and/or obesity are DPP-4 resistant due to their modified molecular structure (Barrera et al., 2009; Katsurada and Yada, 2016). Here, GCG is linked to obesity due to melanocortin 4 receptor deficiency.