The Secretin family is a small family of 15 GPCRs (GPCR-B1) that all have an extracellular hormone-binding domain and bind peptide hormones. The members of this family are the calcitonin and calcitonin-like receptors (CALCR, CALCRL); the corticotropin-releasing hormone receptors (CRHR1, CRHR2); the glucagon receptor (GCGR); the gastric inhibitory polypeptide receptor (GIPR); the glucagon-like peptide receptors (GLP1R, GLP2R); the growth-hormone-releasing hormone receptor (GHRHR); the adenylate cyclase activating polypeptide receptor (PAC1/ADCYAP1R1); the parathyroid hormone receptors (PTHR1, PTHR2); the secretin receptor (SCTR); and the vasoactive intestinal peptide receptors (VIPR1, VIPR2). GLP1R and GLP2R are particularly interesting because of their role in appetite regulation and in the treatment of type 2 diabetes[1].