The purpose of this study is to evaluate the effect of JTT-654 on diabetes as well as the safety, tolerability and pharmacokinetics of JTT-654 in type 2 diabetic patients.

Inclusion Criteria:

1. Have type 2 diabetes;
2. Body mass index (BMI) of ≤ 45.0 kg/m2;
3. Are either untreated with respect to hypoglycemic agents OR are currently being treated with a stable dose of metformin alone.

Exclusion Criteria:

1. Females who are pregnant or breast-feeding;
2. Known medical history or presence of type 1 diabetes or pancreatitis, acute metabolic diabetic complications, presence of unstable or rapidly progressing retinopathy, nephropathy or neuropathy;
3. Acute coronary syndrome or uncontrolled hypertension;
4. Does not meet all diet or previous/concomitant medication restrictions criteria, as described in the protocol.