As it has been reported that differences in the insulinotropic response to exogenous GLP-1 in healthy volunteers were associated with GLP1R rs6923761 (Gly168Ser) and rs3765467 (Arg131Gln) polymorphisms [54], several studies were set up to establish the relationship between these SNPs and the response to GLP-1 RAs in patients with T2DM. This evidence concerns the gene GCG and type 2 diabetes mellitus.