4. Type 2 diabetes may be treated only with metformin (metformin hydrochloride tablets or metformin hydrochloride extended-release tablets) at a total daily dose of 500 mg to the maximum labeled dose. (See Appendix G for List of Drug Trade Names).The dose of metformin must be stable for >8 weeks prior to the Pre-Treatment Visit (Week -4) and throughout the course of the study. The subject must not be on any other pharmacologic or over-the-counter treatments for diabetes.