A Study Assessing Saxagliptin Treatment in Type 2 Diabetic Subjects Who Are Not Controlled With TZD Therapy Alone

All subjects will participate in a lead-in period, and qualifying subjects will continue into a short-term randomized treatment period. Subjects who complete the short-term period will be eligible to enter the long term extension period. Also, subjects in the short-term period who have an elevated blood sugar that requires additional medication for blood sugar control will be eligible to enter the long-term treatment extension period where they will receive metformin (defined as rescue medication) added onto their blinded study medication