With the increasing treatment demands of patients with type 1 diabetes mellitus, pancreatic islet transplantation has emerged as a promising curative therapeutic approach. However, the expansion of donor pools remains a critical challenge for its clinical application. Based on the latest research findings both domestically and internationally, this study systematically explores the application prospects of human-derived islet cells, xenogeneic islet cells, artificial islet cells, and islet organoids in donor pool expansion. Research indicates that human-derived cardiac islet cells, autologous islet cells, and live donors offer diverse options; gene-edited pig islet cells exhibit significant potential in xenotransplantation; stem cell differentiation technologies and direct reprogramming strategies have made the generation of artificial islet cells feasible; and islet organoids, through 3D bioprinting and tissue engineering technologies, further optimize the structure and function of islet-like constructs. However, challenges such as immune rejection and the long-term maintenance of graft functionality remain major obstacles to current technologies. By optimizing donor cell sources, improving immunotolerance strategies, and integrating gene editing with regenerative medicine technologies, the clinical translation prospects of these emerging approaches are becoming increasingly clear. Future research should focus on technological optimization and safety evaluation to provide novel pathways for expanding donor pools and enhancing the clinical efficacy of islet transplantation.