Islet transplantation is the transplantation of isolated islets from a donor pancreas and into another person. It is an experimental treatment for type 1 diabetes mellitus. Once transplanted, the islets begin to produce insulin, actively regulating the level of glucose in the blood.

Islets are usually infused into the patient's liver,. The patient's body, however, will treat the infused islets just as it would any other introduction of foreign tissue: the immune system will attack the islets as it would a viral infection, leading to the risk of transplant rejection. Thus, the patient needs to undergo treatment involving immunosuppressants, which reduce immune system activity. Recent studies have shown that islet transplantation has progressed to the point that 58% of the patients in one study were insulin independent one year after the operation.

In the period from 1999 to 2004, 471 patients with type 1 diabetes have received islet transplants at 43 institutions worldwide.

From http://en.wikipedia.org/wiki/Islet_cell_transplantation