Efficacy of Alogliptin and Pioglitazone in Subjects With Type 2 Diabetes Mellitus

Despite the introduction of new classes of medications for glycemic control, just over half of adults with type 2 diabetes mellitus (T2DM) achieve a glycosylated hemoglobin level less than 7.0%, the American Diabetes Association recommended glycosylated hemoglobin goal. The rising incidence of type 2 diabetes mellitus along with limitations of the currently available treatments suggest the need for new therapies for glycemic control along with the increased requirement for combination therapy in type 2 diabetes mellitus. Thiazolidinediones increase glucose utilization, decrease gluconeogenesis, and increase glucose disposal through an incompletely understood mechanism but one associated with binding of the drug to nuclear receptors known as peroxisome proliferator-activated receptors-gamma. Peroxisome proliferator-activated receptors-gamma are found in tissues important for insulin action, such as adipose tissue, skeletal muscle, and the liver. The greatest concentration of peroxisome proliferator-activated receptors-gamma receptors is in adipose tissue. Thiazolidinediones reduce insulin resistance by enhancing insulin sensitivity in muscle cells, adipose tissue, and hepatic cells (inhibiting hepatic gluconeogenesis) with no direct impact on insulin secretion. Thus, thiazolidinediones improve glycemic control and result in reduced levels of circulating insulin. Pioglitazone HCl (ACTOS®) is a thiazolidinedione developed by Takeda Chemical Industries, Ltd. (Osaka, Japan). Pioglitazone depends on the presence of insulin for its mechanism of action. Worldwide clinical investigation has shown that, as an adjunct to diet and exercise, pioglitazone improves glycemic control when used as monotherapy, and in combination with commonly used antidiabetic medications (ie, sulfonylureas, metformin, or insulin). SYR-322 (alogliptin) is a selective, orally available inhibitor of dipeptidyl peptidase IV currently in development by Takeda Global Research \& Development Center, Inc. as a treatment for type 2 diabetes mellitus. Dipeptidyl peptidase IV is the primary enzyme involved in the in vivo degradation of at least 2 peptide hormones released in response to nutrient ingestion, namely glucagon-like peptide-1 and glucose-dependent insulinotropic peptide. Both peptides exert important effects on islet β-cells to stimulate glucose-dependent insulin secretion and regulate β-cell proliferation and cytoprotection. Glucagon-like peptide-1 also inhibits gastric emptying, glucagon secretion, and food intake. The glucose-lowering actions of glucagon-like peptide-1, but not glucose-dependent insulinotropic peptide, are preserved in patients with type 2 diabetes. Given the complementary mechanisms of action of alogliptin (stimulation of insulin secretion) and pioglitazone (enhancement of insulin sensitivity) and the absence of overlapping safety risks, the introduction of this combination therapy in patients with T2DM could potentially show enhanced glycemic control and allow patients to reach and maintain their HbA1c goal more effectively. This study is designed to determine if the addition of alogliptin to a combination of pioglitazone with metformin can be effective at achieving glycemic control without increasing safety risks versus the titration of pioglitazone to 45 mg with metformin in patients with type 2 diabetes mellitus who are experiencing inadequate glycemic control on a current regimen of metformin.