Abstract: Objective To study the effects of tripterygium on the islet cell function and immunological parameters in patients with late onset autoimmune diabetes mellitus in adults (LADA).Methods Randomly divided into two groups. Test group (n=9) involved in patients with tripterygium and oral hypoglycemic agents (OHA), control group (n=9)with OHA alone.Results ①Compared to control group at 6 months, postprandial blood glucose of test group was decreased and postprandial C peptide of test group was higher.CD + 4 cell of test group was decreased (P<0 05);CD + 4/CD + 8 was decreased in test group at 3 months. ②ICA(+) of 2 patients become negative while no one in control group after 3 months (P<0 05). ③ΔC peptide was correlated with CD + 4/CD + 8(r=-0 36,P<0 05). Conclusion The results suggested that tripterygium played a role in cellular immunity regulation with decrease in the titer of islet cell antibody and tendency to improve islet cell function in early LADA patients.