The aim of the current study is to evaluate the efficacy of alogliptin in combination with pioglitazone in subjects who are inadequately controlled on a thiazolidinedione (pioglitazone or rosiglitazone) alone or in combination with metformin or a sulfonylurea. Individuals who participate in this study will be required to commit to a screening visit and up to 14 additional visits at the study center. Study participation is anticipated to be about 34 weeks (or 8.5 months).