The study has an active phase lasting 15 months and follow-up that continues indefinitely. Patients will receive 10,000 "islet equivalents" per kilogram (2.2 pounds) of body weight. This will likely require two separate transplant procedures from two donors. Before the first surgery, patients will be given anti-rejection (immune suppressing) drugs, including FK506 and rapamycin (orally) and daclizumab (intravenously). The islets will be infused through a tube placed in the portal vein (the large vein that feeds the liver). After surgery, patients will receive insulin intravenously for 24 hours. They will then have an abdominal ultrasound and blood tests to determine liver function. If fewer than 10,000 islets were transplanted, patients will continue insulin treatment, with the dosages adjusted to account for the transplanted islets. They will take Daclizumab every 2 weeks, and FK506 and rapamycin daily. Blood tests to follow how much of these drugs are in the blood stream will be performed daily at first and then weekly after blood levels of these drugs stabilize. They will be given antibiotics to prevent infections. The arginine test will be repeated 2 weeks after the transplant and periodically thereafter. Blood will be drawn weekly to check drug levels, and monthly for other tests. The investigators will track daily insulin requirements, and these will be recorded monthly.