CD4 and type 2 diabetes mellitus: For patients with severe sepsis (with and without T2DM), the percentages of PD-1+ CD4+ T cells and PD-1+ CD8+ T cells were positively correlated with APACHE II score (r = 0.627 and 0.649 respectively, P<0.001) or with SOFA score (r = 0.566 and 0.556 respectively, P<0.001) (Fig 2c–2f), but showed no significant correlation with Hs-CRP, HbA1c, blood glucose levels on admission or lymphocyte count (P>0.05).