Since the 1960's, doctors and scientists have attempted to replace this islet function by performing whole organ pancreas transplantation. While the results of pancreas transplantation have improved dramatically in recent years, this approach has largely been limited to patients with kidney disease who have also needed a kidney transplant. This is because of the risks associated with the surgical procedure and the immunosuppressive drugs required to prevent rejection or the destruction of the transplanted pancreas by the body's immune system. Transplantation of a whole pancreas requires a major operation that is done through an incision in the abdomen. The patient must be under general anesthesia, or asleep, for the entire procedure. Recent clinical experience suggests that islet transplantation may be a useful approach to correct diabetes in humans.