CD4 and type 1 diabetes mellitus: The literature reports that there was acute infiltration of CD4+ T cells in the islet of T1DM patients, the pro-inflammatory cytokine secreted by CD4+ T cells promoted the apoptosis of islet β cells and it has been found that when T cells from T1DM mice are transplanted into normal mice, the islet β cells of normal mice are destroyed and then diabetes occurs31.