Delayed Mycophenolate Mofetil in Single-Donor Islet Allotransplantation in Type 1 Diabetes

Inclusion Criteria: 1. Primary islet allotransplant 2. Type 1 diabetes mellitus, complicated by at least one of the following situations that persist despite intensive efforts in close cooperation with their diabetes care team: 1. Metabolic lability/instability; 2. Reduced awareness of hypoglycemia; 3. Persistently poor glucose control (as defined by HgbA1c\>10% at the end of six months of intensive management efforts with the diabetes care team); 4. Progressive secondary complications. 3. Age 18 and older 4. Able to give written informed consent Exclusion Criteria: 1. Known hypersensitivity to rabbit proteins. 2. Presence of history of panel-reactive anti-HLA antibodies (\>10%). 3. Insufficient cardiovascular reserve. 4. Creatinine clearance \<60 mL/min/m2. 5. Portal hypertension, abnormal liver enzyme tests, or history of significant liver disease. 6. History of malignancy within 5 years. 7. Active peptic ulcer disease. 8. Severe unremitting diarrhea or other gastrointestinal disorders potentially interfering with the ability to absorb oral medications. 9. Pregnancy or breast-feeding. 10. Active infections. 11. Serological evidence of infection with HIV, or HBsAg or HCVAb positive within the previous 12 months prior to transplantation. 12. Negative screen for Epstein-Barr Virus (EBV) by an EBNA method 13. Evidence of infiltrate, cavitation, or consolidation on chest x-ray during pre-study screening. 14. Schizophrenia, bipolar disorder, or major depression that is unstable or uncontrolled on current medications. 15. Ongoing substance abuse; drug or alcohol. 16. Recent history of noncompliance. 17. Any medical condition that, in the opinion of the investigator, will interfere with the safe completion of the trial.