Specifically, the overexpression of Dopamine Receptor D4 (DRD4) gene, Mitogen-Activated protein kinase 13 (MAP3K13) gene, Mannosidase beta (MANBA) gene, Baculoviral IAP repeat containing 2 (BIRC2) gene, Nuclear receptor Binding protein 1 (NRBP1) gene, Kinesin family member 11 (KIF11) gene, Cyclin E2 (CCNE2) gene and Hyaluronidase 3 (HYAL3) gene is negatively correlated with the risk of developing T2DM (OR values all<1). The gene discussed is DRD4; the disease is type 2 diabetes mellitus.