Objective：Through the detection of the relative abundance of immune negative control molecules programmed cell death protein 1（PD-1） mRNA in T-cell subsets and the PD-1 expression on memory T cells from peripheral blood in type 1 diabetes mellitus（T1DM） patients，type 2 diabetes mellitus（T2DM） patients and healthy control separately，to further study the relationship of abnormal expression of PD-1 on memory T cells with the development and progression of T1DM which is characterized by pancreatic β-cell destruction. Methods：Peripheral blood mononuclear cells（PBMCs）were isolated from health control，T1DM patients，and T2DM patients separately；PBMCs were further sorted into CD4+T cells and CD8+T cells，then the relative abundance of PD-1 mRNA was analyzed by fluorescence quantitative PCR；PBMCs were marked by fluorescent antibody CD4-FITC，CD45RO-PE，CCR7-APC，CD8-FITC and PD-1-PerCp separately，then analyzed the expression of PD-1 on CD4+CD45RO+CCR7+Tcm cells，CD4+CD45RO+CCR7-Tem cells，CD8+CD45RO+CCR7+Tcm cells and CD8+CD45RO+CCR7-Tem cells by flow cytometry（FCM）. Results：①The relative abundance of PD-1 mRNA in CD4+T cells from the peripheral blood of the T1DM group was significantly lower than that of the T2DM group and the healthy control group；②There was no abnormality for the relative abundance of PD-1 mRNA in CD8+T cells from the peripheral blood of the T1DM group，compared with the T2DM and healthy control groups；③The expression levels of PD-1 on CD4+CD45RO+CCR7-Tem cells and CD4+CD45RO+CCR7+Tcm cells in the peripheral blood from T1DM patients were significantly lower than those of the healthy control and T2DM group；④There was no significant difference for the expression of PD-1 on CD8+CD45RO+CCR7-Tem cells and CD8+CD45RO+CCR7+Tcm cells between the T1DM group，the T2DM group and the healthy control group. Conclusion：For PD-L1 which is expressed on islet β cells can combine with PD-1 on CD4+Tm cells to negatively regulate cell immunity，so when the expression of PD-1 on CD4+Tm cells is abnormal，cell effect will be further enhanced for the loss of negative regulation，so it may eventually lead to the development of T1DM by destroying islet β cells.