A 12/24-weeks, Open, Multi-centre, Phase IV Study on Safety and Efficacy of 2mg Exenatide Once Weekly (Bydureon) in T2DM Patients.

Inclusion Criteria: * Male or female, 19-75 years of age * diagnosed with type 2 diabetes mellitus * Patients who have not achieved adequate glycaemic control on maximally tolerated doses of these oral therapies; * Metformin * Sulphonylurea * Thiazolidinedione * Metformin and sulphonylurea * Metformin and thiazolidinedione Exclusion Criteria: * Has been treated, is currently being treated, or is expected to require or undergo treatment with any of the following medications: 1. Alpha glucosidase inhibitor or meglitinide within 30 days of screening; 2. Insulin within 2 weeks prior to screening or insulin for longer than 1 week within 3 months of screening; 3. DPP-4 inhibitors within 30 days of screening; 4. Regular use (\> 14 days) of drugs that directly affect gastrointestinal motility within 3 months of screening; 5. Regular use (\> 14 days) of systemic corticosteroids by oral, intravenous, or intramuscular route; or potent, inhaled, or intrapulmonary steroids known to have a high rate of systemic absorption within 3 months of screening; 6. GLP-1 receptor agonist except exenatide within 3 months of screening; * diagnosed with type 1 diabetes mellitus or diabetic ketoacidosis; * type 2 diabetes by beta-cell dysfunction requiring insulin treatment * Has ever used exenatide * Pregnant or breast feeding patients * Hepatic disease (defined by aspartate or alanine transaminase \>3.0 times the upper limit of normal * End-stage renal disease or severe renal impairment (creatinine clearance \< 30 ml/min)