Background: Type-1 diabetes (T1D) is an autoimmune disease in which T lymphocytes destroy insulin-producing β-cells. Control of self-reactive T lymphocytes and recovery of diabetic injury is the end point of T1D. Objective: To investigate generation of tolerogenic dendritic cells (tolDCs) as an innovative method of diabetes therapy. Methods: Lentivirus vector production was achieved by GIPZ mouse CD40 shRNA, psPAX2 and pMD2G plasmids DNA. Purified bone marrow derived DCs were treated with CD40 shRNA, and expression of CD40 and mRNA level were evaluated by flow cytometry and Real-Time PCR, respectively. CD40 knock-down DCs were injected into STZ-induced diabetic mice. Blood glucose; glucose tolerance test and weight were analyzed in different groups. Results: Mice treated with CD40 shRNA transfected DCs showed considerable differences in blood glucose, glucose tolerance, and weight compared to other groups. Also cytokine assays indicated an increase in IL-13 production in the CD40 shRNA group. Conclusion: In streptozotocin-induced diabetic mice model, administration of tolerogenic dendritic cells could improve diabetic parameters.