This is a double-blind (neither physician nor participants knows the treatment that the participant receives), randomized (the study medication is assigned by chance), placebo-controlled (an inactive substance is compared with a medication to test whether the medication has a real effect in a clinical study), parallel-groups study which will be conducted at 2 clinical research centers (CRC) in the US. Approximately 56 participants, ages 25-70 years, with T2DM inadequately controlled on either metformin monotherapy or combination therapy with metformin and a DPP-4 inhibitor, will be enrolled. The study has 3 phases: pre-treatment, double-blind treatment, and post-treatment.