This study is a 24-week single-center, randomized, double-blind, placebo-controlled trial. The trial includes a 3-week early screening and lifestyle education period, 6-week treatment period, and 18-week follow-up period. Chinese type 2 diabetic subjects receiving traditional hypoglycemic treatment were randomly assigned to umbilical cord mesenchymal stem cell or placebo infusion therapy to observe the efficacy and safety of umbilical cord mesenchymal stem cell infusion therapy.

This study is a 24-week single-center, randomized, double-blind, placebo-controlled trial. The trial includes a 3-week early screening and lifestyle education period, 6-week treatment period, and 18-week follow-up period. Chinese type 2 diabetic subjects receiving traditional hypoglycemic treatment（including insulin） were randomly assigned to umbilical cord mesenchymal stem cell or placebo infusion therapy to observe the efficacy and safety of umbilical cord mesenchymal stem cell infusion therapy.

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.