The purpose of this study is to determine if an investigational drug is safe and efficacious for poorly controlled type 2 diabetes mellitus.

Inclusion Criteria:

• Diagnosis of Type 2 Diabetes for at least 3 months.
• Diabetes managed with diet and exercise alone or with either metformin or sulfonylurea alone as an adjunct to diet and exercise.
• Diabetes therapy must be unchanged for at least 3 months prior to screening.
• Females must be of non-childbearing potential (surgically sterilized or at least 1 year post-menopausal, as defined by cessation of menses). Female patients who are not surgically sterilized and who are less than or equal to 45 years should have their post-menopausal status confirmed by FSH greater that 30ng/mL at screening.

Exclusion Criteria:

• Current use of insulin or any antidiabetic agent other than a sulfonylurea agent or metformin.
• Current use of metformin or a sulfonylurea agent in combination.
• History of liver disease.
• History of unstable angina (as defined by the Braunwald system), myocardial infarction, or a coronary revascularization procedure within the past 6 months.
• Currently suspected carcinoma or history of carcinoma in the last 5 years, with the exception of excised superficial lesions such as basal cell carcinoma and squamous cell carcinoma of the skin.