Moreover, sitagliptin (STG), a common antidiabetic drug targeting glucagon-like peptide-1 (GLP-1) signaling via dipeptidyl peptidase 4, is reported not only to improve glucose and lipid metabolism disorders but also to have a protective effect on neuropsychiatric injuries in diabetes mellitus [11] patients or HFD mice [12]. This evidence concerns the gene DPP4 and diabetes mellitus.