• Poorly Controlled Diabetes Mellitus
• Intensive-de-escalation Therapy
• Long-term Regimen Simplification

• Drug: CSII and thereafter combination therapy with wearable devices
  Short-term continuous subcutaneous insulin infusion and thereafter the combination therapy of basal insulin, metformin and vildagliptin; Wearable devices and smart apps will be used to manage and follow-up patients.
• Drug: CSII and thereafter combination therapy
  Short-term continuous subcutaneous insulin infusion and thereafter the combination therapy of basal insulin, metformin and vildagliptin; Traditional ways such as telephone contact will be used to follow-up patients.
• Drug: Traditionally upgrading therapy
  Patients will be applied the combination therapy of basal insulin, metformin and vildagliptin for the entire 12 weeks. Traditional ways will be used to follow-up patients.

• Experimental: Intensive-de-escalation group with intelligent management
  Intervention: Drug: CSII and thereafter combination therapy with wearable devices
• Experimental: Intensive-de-escalation group without intelligent management
  Intervention: Drug: CSII and thereafter combination therapy
• Active Comparator: Traditionally upgrading group
  Intervention: Drug: Traditionally upgrading therapy

Inclusion Criteria:

1. Type 2 diabetes diagnosed according to WHO criteria (1999); With a duration of 1~10 years;
2. With two or more oral hypoglycemic drug used for at least 3 months, including at least one insulin secretagogue in half-max dosage (eg. Glibenclamide 7.5mg/d, gliclazide 60mg/d, glimepiride 3mg/d, glipizide 10mg/d, repaglinide 6mg/d, nateglinide 360mg/d and DPP-4 inhibitor with regular doses);
3. HbA1c of 7.5 to 13% and fasting C-peptide >0.4 nmol/L;
4. Age of 18 to 70 years;
5. BMI of 20 to 35 kg/m²；

6. Capable of and willing to follow doctors' instructions to:

   • Self-monitor blood glucose according to the protocol;

     • Follow the protocol and have regular visits as required; ③ Record and maintain the research diary, as required by the protocol; ④ Keep contact with the investigators and receive phone calls during the study.

Exclusion Criteria:

1. Type 1 diabetes or specific types of diabetes;
2. Those who have received premixed insulin therapy and/or basal - meal insulin and/or basal insulin-oral hypoglycemic agents treatment accumulation for 7 days or more, and those who have received CSII therapy in the last one year, and those who have received GLP-1 analogue within 3 months before screening;
3. Those who have acute diabetic complications (diabetic ketoacidosis, hyperosmotic hyperglycemia coma or lactic acidosis);
4. Those who have severe diabetic microvascular complications (proliferative retinopathy, clinical proteinuria, and glomerular filtration rate less than 45 ml/min, uncontrolled diabetic neuropathy and obvious diabetic autonomic neuropathy);
5. Those with ALT >2.5 times of the upper limit of normal (ULN), bilirubin > 1.5 times of ULN；
6. Those with known macrovascular disease: Patients with acute cerebrovascular accident, acute coronary syndrome, unstable angina, peripheral artery disease who have received vascular intervention or amputation in the 12 months before enrollment; Or chronic cardiac dysfunction with cardiac function grade III or above;
7. Those with poor blood pressure control (systolic blood pressure≥160mmHg and/or sitting diastolic blood pressure ≥110mmHg) and inability to control under 160/110mmhg within 1 week;
8. Serious systemic disease or malignant tumor, chronic diarrhea, etc；
9. Those with drugs that may affect blood glucose for a cumulative time of more than 1 week within 12 weeks, such as oral/venous glucocorticoid, growth hormone, estrogen/ progesterone, high-dose diuretics, antipsychotic drugs. However, low-dose diuretics for antihypertensive purposes (HCTZ < 25mg/d, indapamide < 1.5mg/d) and physiologic dose of thyroid hormone for replacement therapy are not included；
10. Any factors that may affect the participation of the subject in the study or the evaluation of the results；
11. Pregnancy or planned pregnancy, lactation subjects.