In recent years, a new class of antidiabetic drugs has been introduced to treat T2DM, namely, dipeptidyl peptidase 4 (DPP-4) inhibitors, sodium–glucose cotransporter 2 (SGLT2) inhibitors, and glucagon-like peptide-1 (GLP-1) receptor agonists (Davies et al., 2018). This evidence concerns the gene GCG and type 2 diabetes mellitus.