Glucagon-like peptide-1 receptor agonists (GLP-1RAs), which are modified variants of the endogenous GLP-1, such as exendin-4 (Ex-4), reduce blood glucose levels and induce weight reduction, and are hence an effective therapeutic option for type 2 diabetes mellitus (T2DM) [17]. This evidence concerns the gene GLP1R and type 2 diabetes mellitus.