Objective To investigate the antigen-specific T cell functionality in type 2 diabetes mellitus patients. Methods Peripheral blood from 38 type 2 diabetes mellitus patients and 47 health controls (control group) have been collected. The proportions of CD4+and CD8+T cell as well as the ratio of CD4+/CD8+were monitored by flow cytometry. Meanwhile, antigen- nonspecific and specific Th1 responses were compared between two groups through detecting interferon (IFN)-γ, interleukin 2 (IL-2), and tumor necrosis factor (TNF)-α producing cells upon propylene glycol monomethyl ether acetate (PMA)/ionomycine and epstein-barr virus ( EBV) peptides stimulation, respectively followed by an intracellular cytokine staining. Results Compared to control group, the proportion of CD4+T cell and the ratio of CD4+/CD8+were significantly increased in type 2 diabetes mellitus group (P＜0.05) whereas CD8+T cells exhibited no significant difference between two groups. Antigen-nonspecific Th1 responses in type 2 diabetes mellitus patients were significantly decreased, demonstrated by lower percentages of IFN-γ, IL-2, and TNF-α producing CD4+T cells when compared to control group , while CD8+T cells in type 2 diabetes mellitus patients exhibited similar cytokine production patterns. However, when stimulated by EBV specific peptides, the percentages of IFN-γ, IL-2, and TNF-α producing CD8+T cells were significantly higher in type 2 diabetes mellitus patients than those in control group (P＜0.05). HbA1Cwas positively correlated with the percentage of EBV-specific TNF-α producing CD8+T cells (P＜0.05). Conclusion In type 2 diabetes mellitus, the secretion capacity of CD4+and CD8+T cell was significantly decreased and the antigen-specific responses represent the presence of an abnormal activated status, which indicates that chronic hyperglycemia may damage T cells function and aggravate chronic inflammation.