To investigate the expression of Programmed death-1 (PD-1) on T lymphocytes in patients with type 2 diabetes mellitus (T2DM) and severe sepsis, we determined PD-1 expression on CD4+ and CD8+ T lymphocytes of patients with T2DM, severe sepsis, and T2DM combined with severe sepsis. Here, CD4 is linked to diabetes mellitus.