The purpose of this study is to evaluate the safety and efficacy of mesenchymal stem cells (MSCs) derived from human umbilical cord/placenta at a dose of 1.0E+6 MSC/kg for type 2 diabetes.

1. Intervention Details: Biological: umbilical cord/placenta-derived mesenchymal stem cells; Drug: 1. Oral Hypoglycemic Drugs, such as Dimethylbiguanide, Glurenorm and Acarbose, et al. 2. Insulins.

1. 1st transplantation: after finishing all required examines according to protocol in Day 0, umbilical cord/placenta-derived MSCs are transplanted intravenously.
2. 2nd transplantation: after finishing all required examines in Day 90, umbilical cord/placenta-derived-MSCs are transplanted intravenously if the effects of MSC are better than that before.
3. At the same time, patients continue taking the oral hypoglycemic drugs, insulins or the combination of the oral hypoglycemic drugs and insulins which the patients have taken for controlling the higher blood sugar from Day 0 for 1 year. But the dose of the oral hypoglycemic drugs and insulins should be regulated according to the level of blood sugar.

2. Detailed Description:

1. To evaluate the feasibility and safety of transplantation treatment using umbilical cord/placenta-derived mesenchymal stem cells in patients with type 2 diabetes mellitus undergoing the oral hypoglycemic drugs, insulins or the combination of the oral hypoglycemic drugs and insulins.
2. To assess efficacy of transplantation treatment using umbilical cord/placenta-derived mesenchymal stem cells in patients with type 2 diabetes mellitus undergoing the oral hypoglycemic drugs, insulins or the combination of the oral hypoglycemic drugs and insulins.
3. This study will last 2 to 3 years. Participants will be randomly assigned to receive either MSC transplant and the oral hypoglycemic drugs or MSC transplant and insulins or MSC transplant and the combination of the oral hypoglycemic drugs and insulins (experimental group) or the oral hypoglycemic drugs or insulins or the combination of the oral hypoglycemic drugs and insulins (control group). Patients will undergo MSC transplant at the start of the study on Day 0 and take the oral hypoglycemic drugs, insulins or the combination of the oral hypoglycemic drugs and insulins for 1 year. As control, some patients take the oral hypoglycemic drugs, insulins or the combination of the oral hypoglycemic drugs and insulins for 1 year. At the same time, the dose of the oral hypoglycemic drugs and insulins should be regulated according to the level of blood sugar. After 3 months, patients will receive the second MSC transplantation. After six and twelve months from the first transplantation, patients will be evaluated.

Inclusion Criteria:

• Free will taking part in the study and ability to provide written informed consent
• Type 2 diabetes mellitus (as guideline WHO, 1999)
• Age 18-80 years old, Male/Female
• 19≤Body mass index (BMI)≤30㎏/㎡
• Fast blood glucose (FBG)≥7.0 mmol/L, and HbAc1≥7％
• Intravenous insulin tolerance test（ITT）indicate patient being insulin resistance
• Not pregnant or nursing
• No moderate or sever organ dysfunction: Ejection fraction>45%; Creatinine <176 mmol/L
• No active severe viral or fungus infection

Exclusion Criteria:

• Severe concurrent medical condition (e.g., serious heart disease, lung disease, or hematopoietic dysfunction, or liver dysfunction, or kidney dysfunction)
• Active infection requiring treatment
• Unexplained febrile illness
• Known immunosuppressive disease, e.g. HIV infection, or hepatitis B or C infection
• Psychiatric condition that would limit informed consent
• Patient has enrolled another clinical trial study within last 4 weeks.