Objective To study the relationship between interleukin-6(IL-6) and the newly diagnosed type 2 diabetes mellitus with Dampness-Heat Encumbering the Spleen syndrome and the relationship between overweight and IL-6. Methods The plasma levels of IL-6 were detected by radio immunoassay in 40 patients with the newly diagnosed type 2 diabetes mellitus (Dampness-Heat Encumbering the Spleen syndrome 10 cases and the deficiency of Qi and Yin syndrome 10 cases)and 10 healthy adults. The changes of body mass index (BMI) and waist-hip ratio (WHR) were observed and analyzed in each group. Results The level of IL-6 in blood plasma of patients with the newly diagnosed type 2 diabetes mellitus were obviously higher than that in normal group (P< 0.01); IL-6 level in patients with Dampness-Heat Encumbering the Spleen syndrome and overweight were obviously higher than those with the deficiency of Qi and Yin syndrome (P< 0.01). Conclusion Interaction between the high level of cytokines and (or) overweight may affect the normal immune function, and promote the development of diabetes, especially in patients with Dampness-Heat Encumbering the Spleen syndrome. The high level of IL-6 may indicate the large possibility of future T2DM and can be considered as a new diagnosis of T2DM syndrome differentiation. Key words: Type 2 diabetes mellitus; IL-6; Dampness-Heat Encumbering the Spleen