One of the alternative therapeutic methods is herbal medicine. Leontice leontopetalum belongs to Berberidaceae family. The aim of study was investigated the extract of LL on human pancreatic beta cell-treated with STZ. Materials and methods: The human pancreatic beta cell (1.1B4) line was used the current study. LL’s extracts (1, 10, 100, and 1000 ug/ml) were supplemented in media for twenty-four hours and/or after STZ treatment (10 and 20 mM). Cells survivals (MTT), cells proliferation were shown by using xCelligence. Insulin content and releasing were measured at 1.1, 8.4 and 16.7 mM glucose concentrations. Results: The result of MTT was shown that cell survival was decreased, based on dose-dependent. When looked at xCelligence results, cell proliferation in STZ groups and the lowest and highest concentrations of LL were attenuated in a dose-dependent manner. Also, cotreatments of LL and STZ were decreased as well. The result of insulin-releasing on glucose induction was shown that STZ concentration gave rise to reduce insulin content at low and high glucose levels. Also, co-treatment of LL and STZ attenuated insulin content based on dose. Conclusion: It was considered that LL treatment led to increased insulin realizing, resulting from decreasing insulin content in diabetic beta cells, but decrease cell survival.