CD4 and type 2 diabetes mellitus: A decrease in immune-effective CD4+/CD8+ TCRβ+ T cells and an increase in characteristically immune-suppressive TCRγδ+ CD4−CD8− T cells has been demonstrated in T2DM animal models; Further, the studies demonstrated a decrease in mucosa-protecting cells, showing possible effects of T2DM on the innate immune system: nasal immunity (15).