Efficacy and Safety of Umbilical Cord Mesenchymal Stem Cells Transplantation in Patients With Type 2 Diabetes Mellitus

Inclusion Criteria: 1. Type 2 diabetes； 2. The course of diabetes is 5-15 years; 3. 20kg/m2≤body mass index (BMI)≤30 kg /m2； 4. 7.5% ≤HbA1c≤10%； 5. Insulin dose and other oral antidiabetic drugs doses should be stable over the 3 months prior to randomization. Exclusion Criteria: 1. Heavy allergic constitution or an allergy to any component used in cell culture. 2. Being treated with drug (Glucocorticoids，Tricyclic Antidepressive Agents,etc.) affect the metabolism of glucose in the past 1 month; 3. other causes of diabetes; 4. All kinds of acute complications such as diabetic ketoacidosis and non-ketohyperosmotic syndrome were screened in the past 6 months; 5. Having evidence of ongoing or frequent/severe hypoglycemia in the past 6 months; 6. Severe cardiovascular and cerebral events：occurrence of heart failure NYHA Classification III or IV, myocardial infarction, cerebral infarction, cerebral hemorrhage within 6 months before the observation period; 7. Patients with abnormal liver and kidney function: AST and ALT exceeding 2.5 times of the normal upper limit, and serum creatinine exceeding 1.5 mg/dl for men, exceeding 1.4 mg/dl for women; 8. Positive results of HbsAg、Anti-HCV、HIV or syphilis; 9. Patients suffering from other serious systemic diseases (such as malignancy, central nervous system,cardiovascular system, blood system, digestive system,endocrine system,respiratory system, genitourinary system, immune system and); 10. Ongoing pregnancy or absence of effective contraception in women with childbearing potential; 11. Patients who had received other stem cell therapy before screening.