The implantation of a part of the pancreas (e.g., cells of the islets of Langerhans) or the entire gland from a donor into a patient whose own pancreas is no longer functioning. In the diabetic patient, pancreas transplantation provides an endogenous source of insulin and may be combined with kidney transplantation. The risks of the surgery and the immunosuppression associated with transplantation must be weighed against the kidney, nerve, and retinal damage associated with uncontrolled diabetes mellitus. Some potential complications of the procedure include infections, blood clotting in the vessels that supply the graft, hypoglycemia, bladder injury, and organ rejection. To prevent rejection, immunosuppressive drugs, such as tacrolimus, mycophenolate mofetil, cyclosporine, and corticosteroids, may be used. Episodes of rejection are treated with the monoclonal antibody OKT3. The 1-year survival rate of combined pancreas-kidney transplants is about 80%, when performed at institutions where the procedure is done frequently.