Thiazolidinediones are peroxisomal proliferator-activated receptor agonists reducing insulin resistance in muscle cells, adipose (fat) tissue, and hepatic cells (inhibiting hepatic gluconeogenesis) with no direct impact on insulin secretion. Thus peroxisomal proliferator-activated receptor agonists improve glycemic control and result in reduced levels of circulating insulin. Peroxisomal proliferator-activated receptors are found in various tissues important for insulin action, with the greatest concentration of these receptors is in adipose tissue.