This 4 arm study will evaluate the tolerability, efficacy and pharmacodynamics of different doses of a GLP-1 analogue in patients with type 2 diabetes who are treated with a stable dose of metformin. Patients will be randomized to receive either subcutaneous placebo, or subcutaneous GLP-1 analogue (at a dose of 20mg, or a starting dose of 20mg escalating to either 30mg or 40mg), weekly. All patients will continue on their existing metformin treatment regimen throughout the study. The anticipated time on study treatment is <3 months, and the target sample size is 100-500 individuals.

Inclusion Criteria:

• male,and post-menopausal or surgically sterilized female, patients, 18-75 years of age;
• type 2 diabetes mellitus, with stable metformin treatment for >=3 months;
• HbA1c >=7.0% and <=9.5% at screening;
• stable weight +/-10% for >=3 months before screening.

Exclusion Criteria:

• type 1 diabetes mellitus;
• clinically significant gastrointestinal disease;
• treatment with any anti-hyperglycemic medication other than metformin monotherapy during last 3 months;
• use of weight-lowering medications in the last 3 months;
• uncontrolled hypertension;
• previous exposure to GLP-1 or GLP-1 analogues.