Bacteroides ovatus crosses the damaged intestinal barrier and enters the systemic circulation, while too much Bacteroides ovatus in the peripheral blood will drive the expansion of MAIT cells in the body, thus producing more IL-17, which can induce pro-inflammatory reactions in the body through various pathways, thereby inducing insulin resistance and increasing the risk of developing T2D. The gene discussed is IL17A; the disease is type 2 diabetes mellitus.