GLP1R and type 2 diabetes mellitus: The glucagon-like peptide-1 receptor (GLP-1R) is a peptide hormone class B GPCR whose activation stimulates the glucose-dependent stimulation of insulin and decreases glucagon secretion.183–185 For such peptide receptors, allosteric pockets on GPCRs may be easier to target for small-molecule drugs than orthosteric drugs.186 Therefore, highly potent agonists and PAMs of GLP-1R must be developed to treat type 2 diabetes.187–191