This 3 arm study will assess the efficacy, safety and tolerability of taspoglutide compared to placebo in patients with type 2 diabetes mellitus inadequately controlled with diet and exercise. Patients will be randomized to one of 3 treatment arms: taspoglutide 10mg sc once weekly, taspoglutide 20mg sc once weekly (after 4 weeks of taspoglutide 10mg sc once weekly) or placebo. After the first 24 weeks patients on placebo will be switched to taspoglutide 10mg once weekly or taspoglutide 20mg once weekly (after 4 weeks of taspoglutide 10mg once weekly). The anticipated time on study treatment is 1 year, and the target sample size is 100-500 individuals.

Inclusion Criteria:

• adult patients, 18-80 years of age;
• drug naive patients with type 2 diabetes uncontrolled with diet and exercise;
• tested negative for anti-glutamic acid decarboxylase (anti-GAD) antibodies;
• C-peptide (fasting) >=1.0ng/mL
• HbA1c >=6.5% and <=10.0% at screening;
• BMI >=25 (>23 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 mellitus or acute metabolic diabetic complications such as ketoacidosis or hyperosmolar coma in the previous 6 months;
• evidence of clinically significant diabetic complications;
• symptomatic poorly controlled diabetes;
• myocardial infarction, coronary artery bypass surgery, post-transplantation cardiomyopathy or stroke within the previous 6 months;
• known hemoglobinopathy or chronic anemia.