The purpose of the study is to assess the safety and efficacy of FK614 in type 2 diabetic subjects receiving sulfonylurea (SU) monotherapy.

This is a prospective randomized, double-blind, placebo controlled, parallel group, Phase 2 study. Subjects meeting selection criteria will be randomly assigned to receive 12 weeks twice daily (BID) dosing with FK614 or placebo. Enrollment for this study will be approximately 200 patients.

Inclusion Criteria

• Has history of type 2 diabetes mellitus for at least 1 year
• Has been taking current sulfonylurea (SU) for at least 3 months. Subjects currently taking metformin may be eligible to be switched.
• Has not received any oral antidiabetic medication other than an SU or taken regularly prescribed insulin for at least 3 months

Exclusion Criteria

• Has type 1 diabetes mellitus
• Has uncontrolled hypertension, i.e., systolic BP >170 or diastolic BP > 95 mm Hg.
• History of congestive heart failure