Our hypothesis is that a successful clinical islet transplant program can be established at the University of Wisconsin using a steroid -free, sirolimus- and low dose tacrolimus - based immunosuppressive drug regimen (Edmonton protocol). We intend to answer the following research questions: 1) will treatment of islet transplant recipients with thiazolidinediones (i.e. pioglitazone) enhance post-transplant islet function and reduce the number of islets necessary to achieve adequate metabolic control? 2) which type 1 diabetic patients are optimal candidates for islet transplantation (i.e. islet transplant alone or islet after kidney transplantation)? 3) Can cadaver donor pancreases, which are ordinarily discarded and not used for pancreas transplantation be used for islet transplantation?