Method for transplanting insulin-producing cells

In the present invention, insulin-producing cells are transplanted into the subcutaneous fat tissue of the inguinal region or the like of a diabetic patient, providing a new mechanical cellular transplantation method that can potentially resolve obstacles currently faced in clinical pancreatic islet transplantation, i.e., the evaluation of transplant pancreatic islet cells, the difficulty in harvesting said cells, and the low transplantation efficiency.　Moreover, the present invention is a breakthrough method for treating a diabetic patient merely by transplanting, into a recipient, the same number or a lower number of insulin-producing cells present in one donor. The present invention can alleviate the problem of insufficient transplanted insulin-producing cells. Moreover, the present invention provides evidence that insulin/glucagon double-positive cells only appear in the pancreatic islet cells transplanted to the subcutaneous fat tissue of the inguinal region of mice, and that these insulin/glucagon double-positive cells provide a new in-vivo model of β cell differentiation.