GCG and obesity due to melanocortin 4 receptor deficiency: Early clinical results for a dual agonist peptide for both the GLP-1 and GIP receptors support a path forward for GIPR agonist approaches for treating T2D and/or obesity [23, 53]; however, pre-clinical data from multiple independent studies also validate a clinical strategy that employs a GIPR antagonist [38, 40, 45, 46].