BACKGROUND: Plantamajoside (PMS) has shown potential in mitigating cell damage caused by high glucose (HG) levels. Despite this, the precise therapeutic effects of PMS on type 2 diabetes mellitus (T2DM) and the underlying regulatory mechanisms require further exploration. AIM: To investigate PMS therapeutic effects on T2DM in mice and elucidate its mechanisms of action through METHODS: An RESULTS: PMS intervention ameliorated cell injury in HG + PA-induced MIN6 cell damage. Transcriptomic analysis revealed that protein processing in the endoplasmic reticulum and apoptosis pathways were enriched in cells treated with PMS, with significant downregulation of the gene Dnajc1. Further validation indicated that PMS significantly inhibited the expression of apoptosis-related factors (Bax, CytC) and endoplasmic reticulum stress (ERS)-related factors [ATF6, XBP1, Ddit3 (CHOP), GRP78], while promoting the expression of Bcl-2 and Dnajc1. Additionally, the inhibitory effects of PMS on ERS and apoptosis were abolished upon Dnajc1 silencing. Furthermore, CONCLUSION: PMS intervention could alleviate pancreatic tissue damage effectively. The mechanism of action involves Dnajc1 activation, which subsequently inhibits apoptosis and ERS, ameliorating damage to pancreatic β-cells.