Described are Neo-lslets comprising: a) dedifferentiated islet cells and mesenchymal and/or adipose stem cells； or b) redifferentiated islet cells and mesenchymal and/or adipose stem cells where the cells have been treated so as to facilitate redifferentiation. Further described herein are methods of generating Neo-lslets. Also described are methods of treating a subject, the methods comprising: providing to the subject Neo-lslets described herein. Additionally described are methods of treating a subject suffering from Type 1 Diabetes Mellitus, Type 2 Diabetes Mellitus, and other types of insulin-dependent diabetes mellitus, or impaired glucose tolerance by providing to the subject Neo-lslet as described herein. Additionally described are methods of treatment comprising intraperitoneal administration of islet-sized Neo-lslets composed of high numbers of mesenchymal stem cells and cultured islet cells.
