INTRODUCTION: Many patients struggle to control glucose without side effects. Due to their immunomodulatory and regenerative properties, mesenchymal stem cells (MSCs) might treat Diabetes Mellitus (DM). The authors employed this meta-analysis to evaluate the efficacy and safety of umbilical cord MSCs (UCMSCs) for DM management. METHODS: The PubMed, Cochrane, WOS, Embase, and Scopus databases were searched for randomized controlled trials (RCTs) investigating the effects of UCMSCs on DM (Types 1, 2) till January 2024. Patient demographics, interventions, and outcomes, including glycated hemoglobin (HbA1c%), C-peptide levels, and insulin requirements, were extracted. A comprehensive meta-analysis software was used. RESULTS: Eight CTs of 334 patients (172 experimental and 162 controls) were included. UMSCs treatment substantially lowered HbA1c levels (MD = -1.06, 95% CI [-1.27, -0.85], CONCLUSION: UMSCs therapy reduced HbA1c and insulin requirements, and increased C-peptide levels. Multicenter clinical trials are required to confirm the long-term efficacy and safety of UMSC therapy.