transplanted into the portal vein of patients with type 1 diabetes mellitus (T1DM) in such a way so as to achieve insulin independence for the recipient. The protocol will employ a defined islet isolation procedure, percutaneous islet infusion into the recipient s portal vein via an intra-portal catheter, tight glycemic control during the peri-transplant period, and a novel immunosuppressive protocol that avoids glucocorticoids. Up to 20 patients between the ages of 18 and 65 who have been diagnosed with T1DM for at least five years and who have no detectable endogenous insulin producing capacity will be enrolled. Since the study calls for at least 10,000 islet equivalents (IEQs) per kilogram recipient body weight to be transplanted, and since a typical human pancreas yields approximately 2.0 to 4.0 times 105 IEQs, most protocol enrollees will require islets isolated from two different donors. Islets will be transplanted shortly after isolation, and since human donor pancreata are available at unpredictable times, the timing of the islet transplant procedure will also be unpredictable. The study s primary end-point will be insulin independence at one year following the transplantation of at least 10,000 IEQs per kilogram recipient body weight. Secondary endpoints will be evidence of partial islet function as reflected by stimulated c-peptide secretion, a Hgb A1c of 7.0% or less, and the absence of severe hypoglycemia. Additional secondary endpoints will be to determine: 1) if any immune parameters are predictive of islet loss, 2) if islet transplantation has any effect on renal function and 3) if the protocol influences fasting lipid profiles.