The purpose of this study is to assess changes from baseline in insulin sensitivity, hepatic fat content and beta cell function after approximately 24-25 weeks of treatment with canagliflozin compared to placebo in participants with type 2 diabetes mellitus (T2DM) with inadequate glycemic (blood sugar) control on metformin monotherapy or on combination therapy with metformin and a dipeptidyl peptidase-4 (DPP-4) inhibitor.