Inclusion criteria:

• Type 2 diabetes.
• HbA1c (a measure of the average amount of sugar in blood over the last 2 or 3 months) levels are between 7.0 and 9.0.
• Taking 850mg or more per day metformin, but not taking any other diabetes medications.
• Must be medically able and willing to discontinue diabetic medications from at least 2 weeks prior to first study dose until the last study assessment.
• Diabetic subjects who have not yet started taking diabetes medications or whose diabetes is controlled by diet alone may also be eligible to enroll if their HbA1c is within 7.5 to 9.0.
• Women may be eligible if they are post-menopausal or surgically sterile.
• If taking ACE inhibitors, beta-blockers, calcium channel blockers, or statin type drugs, you may be eligible if your dose has been stable for at least 30 days prior to the start of the clinical trial.

Exclusion criteria:

• Using illicit drugs, or have antibodies to hepatitis B, hepatitis C, or HIV.
• Have any major health problems other than type 2 diabetes.
• Require insulin therapy or oral antidiabetic medication other than metformin.
• Subjects who have had a urinary tract infection within 4 weeks of the start of the study or who have kidney disease.
• Subjects with either low or high blood pressure.
• Men who are unwilling to abstain from intercourse, or use a condom with a pregnant or nursing female, or who are unwilling to use a condom with another form of contraception with a female who could become pregnant.