A Phase 3, Multicenter, Randomized, Double-blind, Placebo-controlled, Parallel-group, Comparative Study and a Phase 3, Multicenter, Open-label, Long-term Study to Evaluate the Safety and Efficacy of SYR-472 When Orally Administered at a Dose of 100 mg Once Weekly as an add-on to Insulin Therapy in Patients With Type 2 Diabetes Mellitus and Inadequate Glycemic Control Despite Treatment With Insulin Preparations in Addition to Diet and/or Exercise Therapy

The purpose of this study is to evaluate the efficacy and safety of SYR-472 when administered at a dose of 100 mg once weekly as an add-on to insulin therapy (SYR-472 100 mg combination/SYR-472 100 mg combination group) using insulin preparation alone/ SYR-472 100 mg combination group as a control in patients with type 2 diabetes mellitus and inadequate glycemic control despite treatment with insulin preparations in addition to diet and/or exercise therapy; and to evaluate the long-term efficacy and safety of SYR-472 when administered at a dose of 100 mg once weekly as an add-on to insulin therapy in patients with type 2 diabetes mellitus and inadequate glycemic control despite treatment with insulin preparations in addition to diet and/or exercise therapy.