The aim of this study was to investigate the changes of Helper T cells 17 (Th17 cells), Regulatory T cells (Treg cells), Treg/Th17, Interleukin-17 (IL-17) and Interleukin-10 (IL-10) in patients with type 2 diabetes mellitus (T2DM).Four electronic resource databases were searched from their inception to 1 August 2021. Case-control studies about changes of Th17 cells, Treg cells, Treg/Th17, IL-17 and IL-10 in patients with T2DM were retrieved. We performed this meta-analysis via RevMan V.5.3 and Stata14.20 studies with 1242 individuals were included in the meta-analysis. Compared with the controls, the patients with T2DM had significantly increased levels of percentage of Th17 cells (SMD, 1.74; 95% CI, 0.47-3.01; p 0.001), IL-17 (SMD, 2.17; 95% CI, 0.06-4.28; p 0.001), IL-10 (SMD, 1.20; 95% CI, 0.81-1.59; p = 0.003), but decreased levels of percentage of Treg cells (SMD, -1.17; 95% CI, -2.22 to -0.13; p 0.001) and Treg/Th17 ratio (SMD, -4.43; 95% CI, -7.07 to -1.78; p 0.001). Subgroup analysis showed that percentage of CD4Adaptive immune system indeed plays an essential role in the process of T2DM. Imbalance between Th17 and Treg triggers pro-inflammatory environment in patients with T2DM.