Therapeutic agents have been developed to address each of the major functional metabolic defects associated with type 2 diabetes: decreased beta-cell function, elevated hepatic glucose output, and insulin resistance. Thiazolidinediones increase glucose utilization, decrease gluconeogenesis, and increase glucose disposal by binding to nuclear receptors known as peroxisome proliferator-activated receptors. 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 without predisposing patients to hypoglycemia. Peroxisome proliferator-activated receptors 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.