This study will assess the efficacy, safety and tolerability of increasing doses of GK Activator (2) in patients with type 2 diabetes whose condition has not been optimally controlled with one previous oral antihyperglycemic agent. After a 2 week washout from their previous antidiabetic therapy, patients will receive GK Activator (2) orally, twice a day for 12 weeks, at increasing doses of 25mg bid to 200mg bid; doses will be titrated to achieve a target fasting glucose level (FPG) of <100mg/dL. The anticipated time on study treatment is <3 months, and the target sample size is 100-500 individuals.