Patient description: The patient is a 24-year-old man who has had type 1 diabetes for 11 years. He presents to the emergency room with hyperglycemia and concern for possible diabetic ketoacidosis after not taking his insulin for 3 days. The patient reports that he is currently homeless and has lost his supply of insulin, syringes, glucometer, and glucose testing supplies. The patient states that at the time of his initial diagnosis with type 1 diabetes he was hospitalized with a glucose value >1000 mg/dL. At the time, he was experiencing polyuria, polydipsia, and polyphagia. He reports that he has been on insulin since the time of his diagnosis, and he has never been prescribed oral agents for diabetes management. Most recently, he has been using insulin glargine 55 units once daily, and insulin aspart sliding scale 3 times daily. The patient has had previous episodes of diabetic ketoacidosis, for which he was hospitalized. With this episode of hyperglycemia, he is not experiencing any nausea, vomiting, or abdominal discomfort, and he appears well. His lab studies showed: A1c: 11.3% Creatinine: 0.9 mg/dL with eGFR >60 mL/min Aspartate aminotransferase (AST): 17 U/L Alanine aminotransferase (ALT): 14 U/L Beta-hydroxybutyrate: 0.1 mmol/L Bicarbonate: 25 mEq/L Anion

Clinical trial eligibility criteria: eligible ages (years): 18.0-999.0,  Long-standing Type 1 Diabetes Mellitus Informed consent obtained before any investigation-related activities. Investigation-related activities are any procedure that would not have been performed during normal management of the subject. 2. Diagnosis of type 1 diabetes mellitus for > 5 years 3. Men or women > 18 years of age at the time of enrolment 4. Involvement in intensive diabetes management defined as self-monitoring of blood glucose level no less than a mean of three times per day averaged over each week and by the administration of three or more insulin injections per day or insulin pump therapy. This management must be under the direction of a diabetologist or diabetes specialist during the 12 months prior to study enrolment  Body mass index (BMI) > 30 kg/m² 2. Insulin requirement of > 1.0 Units/kg/day 3. HbA1c > 10 % (DCCT) 4. Random C-peptide > 0.003 nmol/l 5. Known untreated active proliferative diabetic retinopathy changes or increasing macular oedema 6. Renal failure (Glomerular Filtration Rate <60 ml/min) 7. Women of childbearing potential who are pregnant, breast-feeding or intend to become pregnant or unwilling to use adequate contraceptive methods for the duration of the trial (implants, injectables, combined oral contraceptives, hormonal intrauterine device, sexual abstinence or vasectomised partner). 8. Active infection including hepatitis B, hepatitis C, HIV, Tbc 9. Any history of malignancy except for completely resected squamous or basal cell carcinoma of the skin 10. Known active alcohol or drug abuse. 11. Any coagulopathy or medical condition that would require long-term anticoagulant therapy (e.g., Warfarin) after transplantation (low-dose aspirin treatment is allowed) or subjects with an international normalized ratio (INR) > 1.5. 12. Severe co-existing cardiac disease, characterized by any of these conditions: 1. Recent myocardial infarction (within past 36 weeks) 2. Evidence of ischemia on functional cardiac exam within the last year 3. Left ventricular ejection fraction < 30 % 4. Cardiovascular conditions within 36 weeks prior to this trial: i. Decompensated heart failure New York Heart Association (NYHA) class III or IV ii. Unstable angina pectoris iii. Coronary arterial bypass graft iv. Coronary angioplasty 13. Inadequately treated blood pressure elevation (systolic BP > 160 mmHg or diastolic blood pressure > 100 mmHg) 14. Use of any medications to treat diabetes other than insulin within 4 weeks of enrolment 15. Administration of live attenuated vaccine(s) within 8 weeks of enrolment 16. Any previous organ transplant 17. Treatment with any immunosuppressive drug 18. Any medical condition that, in the opinion of the investigator, will interfere with safe participation in the trial (e.g., systemic glucocorticoids) 19. Known or suspected allergy of hypersensitivity to trial product(s) or related products 20. The receipt of any investigational product within 30 days of screening for this trial 21. Any scheduled transplant in addition to the islet transplantation 22. Fulfillment of for clinical pancreas or islet transplantation