A Study of Taspoglutide Versus Exenatide for the Treatment of Patients With Type 2 Diabetes Mellitus Inadequately Controlled With Metformin, Thiazolidinedione or a Combination of Both.

Inclusion Criteria: * adult patients, 18-75 years of age; * type 2 diabetes receiving metformin and/or pioglitazone or rosiglitazone for at least 12 weeks; * HbA1c \>=7.0% and \<=10% at screening; * BMI \>=25kg/m2 (\>23kg/m2 for Asians) and \<=45kg/m2 at screening; * stable weight +/- 5% for at least 12 weeks prior to screening. Exclusion Criteria: * history of type 1 diabetes, diabetes resulting from pancreatic injury or secondary forms of diabetes; * history of acute metabolic diabetic complications within the previous 6 months; * evidence of clinically significant diabetic complications; * known proliferative diabetic retinopathy; * myocardial infarction (MI), coronary artery bypass surgery, post-transplantation cardiomyopathy (PTCM) or stroke within the past 6 months; * any abnormality in clinical laboratory test or ECG, which precludes safe involvement in the study as judged by the investigator; * known hemoglobinopathy or chronic anemia; * clinically significant gastrointestinal disease.