Objective:To investigate the effects of silent information regulator 1 (Sirt1) over-expression on high glucose-induced proliferation and transforming growth factor-β1 (TGF-β1) expression in human glomerular mesangial cells (HMCs). Methods: HMCs were cultured in vitro. The HMCs were transfected with either lentiviral vectors containing the Sirt1 cDNA (LV-Sirt1) or empty vectors (LV-CTL). The expression of Sirt1 protein was detected by Western blot. Those HMCs transfected with lentiviral vectors were divided into 4 groups including normal glucose (5.5 mmol/L) plus LV-CTL (NG+LV-CTL), high glucose (30 mmol/L) plus LV-CTL (HG+ LV-CTL), normal glucose plus LV- Sirt1 (NG+LV-Sirt1), and high glucose plus LV-Sirt1 (HG+LV-Sirt1) groups. Those untransfected HMCs were cultured at normal glucose (NG), normal glucose plus mannitol (5.5 mmol/L glucose + 24.5 mmol/L mannitol ) (NM) or high glucose (30mmol/L) (HG) as control. After treatment for different periods, the cell proliferation of each group was examined using CCK-8 detection kit, and the levels of mRNA and protein of TGF-β1 from each group were measured through real-time polymerase chain reaction (PCR) and Western blot, respectively. Results: The HMCs, which was stably over-expressed Sirt1 protein, was obtained after recombinant lentivirus infection and puromycin selection. Compared with the NG group, the proliferation levels of HMCs from the HG, HG+LV-CTL and HG+LV-Sirt1 groups on 12, 24 and 48 hours were increased significantly (each P < 0.01). However, the proliferation level of the HG+LV-Sirt1 group is significantly lower than that in the HG and HG+ LV-CTL groups. As compared to counterparts of the HG and HG+ LV-CTL groups, the levels of mRNA and protein of TGF-β1 from the HG+LV Sirt1 group were decreased significantly (each P < 0.01). The levels of mRNA and protein of TGF-β1 from the HG treated groups were higher than those of the NG group (each P < 0.01). In addition, there were no difference on the levels of mRNA and protein of TGF-β1 among NG, NM, NG+LV-CTL and NG+LV Sirt1 groups (each P > 0.05). Conclusion: Sirt1 over-expression can inhibit cell proliferation and TGF-β1 expression of HMCs induced by high glucose treatment. Sirt1 gene may become a new therapeutic target of diabetic nephropathy.