This is a 16-week, Single-center, Randomized, Open Label, Parallel Controlled Group Comparison of the Comprehensive Glycemic Control of Exenatide and Insulin Glargine on Type 2 Diabetes Patients Inadequately Controlled With Metformin Monotherapy.

Screening will be made to select eligible patients, then 44 patients receiving a stable dose of metformin (≥1500 mg daily) will be randomized (1:1) to receive exenatide or insulin glargine for 16 weeks. Exenatide will be administered twice daily by subcutaneous injection 30- 60 minutes before breakfast and dinner; the dose was 5 μg twice-daily for the first 4 weeks of treatment and 10 μg thereafter. Insulin glargine will be administered once daily at bedtime by subcutaneous injection. The dose of insulin glargine will initiate at ≥8 IU once-daily, and titrate based on a dosing algorithm targeting fasting blood glucose (FPG)<6.1 mmol/L. Titration is only allowed in first 4 weeks. At the end of the study, data will be collected and analyzed.

Inclusion Criteria:

1. Provision of informed consent prior to any study specific procedures
2. Type2 diabetic patients had been on stable, maximum tolerated doses of metformin (≧1500mg/d, ≧8 weeks)
3. Male or female age ≧ 18 years and ≦70 years old
4. HbA1c ≧7.0 and ≦10%
5. BMI ≧ 24 kg/m2

Exclusion Criteria:

1. Known or suspected allergy to trial products or related products.
2. Impaired renal function defined as serum-creatinine ≥ 1.5 mg/dl (≥ 133 umol/l).
3. Acute or chronic disease which may cause tissue hypoxia such as respiratory failure or shock.
4. Abnormal liver function, alanine transaminase or aspartate aminotransferase ≥ 3 fold normal upper limit, Total bilirubin ≥ 2 normal upper limit, acute alcohol intoxication, alcoholism.
5. Subjects has a clinically significant, active (or over the past 12 months) cardiovascular history (including a history of myocardial infarction (MI), arrhythmias or conduction delays on ECG, unstable angina, or decompensated heart failure (New York Heart Association-class Ⅲ and Ⅳ).
6. Proliferative retinopathy or muscular oedema requiring acute treatment.
7. Pregnant or positive pregnancy test at screening, nursing mother, or unwillingness to use adequate contraception (adequate contraceptive measures are sterilization, intrauterine device, oral contraceptives or barrier methods).
8. Treatment with systemic corticosteroids within the past two months prior to screening.
9. Type 1 diabetes mellitus.
10. Receipt of any investigational drug within 1 month prior to this trial.