Background: Type 2 diabetes (T2D) is a progressive disease. Many drugs currently being used for the management of T2D have minimal effect on pancreatic beta cells regeneration. Cell-based therapies might provide potential benefits in this aspect. Methods: A pilot study in five T2D patients with 12 months follow-up was performed to evaluate the effect of autologous bone marrow mononuclear stem cells (BM-MNCs) infusion into pancreatic arteries on the insulin requirement, beta-cell function, insulin resistance, and systemic inflammatory marker (CRP). Results: The primary endpoint, a 50 % reduction of total insulin doses from baseline, was not achieved in this study. However, a trend of increasing fasting C-peptide (p = 0.07) and C-peptide 60′ (p = 0.07) and 90′ (p = 0.07) after a mixed-meal tolerance test was observed 12 months post-infusion compared to baseline levels. A similar result was observed for the homeostatic model assessment of beta cell function (HOMA1-B), an index for beta cell function. No improvement was observed for insulin resistance measured by homeostasis model assessment of insulin resistance (HOMA1-IR) and systemic inflammatory parameter. Conclusion: Intraarterial pancreatic autologous BM-MNCs infusion might potentially improve beta cell function in T2D patients, although further study is needed to confirm this finding. © 2023