Abstract-Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors belonging to the nuclear hormone receptor superfamily. The 3 PPAR isotypes, PPAR-␣, PPAR-␥, and PPAR-␦, play a key role in the regulation of lipid and glucose metabolism. Obesity and the interrelated disorders of the metabolic syndrome have become a major worldwide health problem. In this review, we summarize the critical role of PPARs in regulating inflammation, lipoprotein metabolism, and glucose homeostasis and their potential implications for the treatment of obesity, diabetes, and atherosclerosis. Key Words: PPARs Ⅲ atherosclerosis Ⅲ obesity Ⅲ diabetes T ype 2 diabetes is a complex metabolic disorder that affects between 6% and 20% of the population in Western industrialized societies. Around the globe, the prevalence of type 2 diabetes is expected to increase exponentially, especially among the young. 1 Type 2 diabetes is characterized by hyperglycemia, insulin resistance, and progressive loss of -cell function throughout the course of the disease and is associated with dyslipidemia, hypertension, and obesity (components of the metabolic syndrome). 2 Both type 1 and type 2 diabetes are considered a coronary artery disease (CAD) risk equivalent. 3 However, CAD often precedes the onset of diabetes, because 50% of patients with new onset type 2 diabetes already have a CAD diagnosis.Components of the metabolic syndrome-insulin resistance, hypertension, low high-density lipoprotein (HDL), and hypertriglyceridemia-are themselves CAD risk factors, whereas hyperglycemia additionally contributes to vascular damage. Whether hyperinsulinemia and insulin resistance directly contribute to vascular damage is controversial and under active investigation. 4 Although type 1 and 2 diabetes are associated with increased atherosclerosis, the pathogenesis of CAD in diabetes is multifactorial. Changes in metabolic factors, increased oxidative stress and glycoxidation, endothelial dysfunction, inflammation, and the prothrombotic state, observed in diabetics play a role in cardiovascular complications of diabetes. 5 Initially, type 2 diabetes was referred to as disorder of carbohydrate metabolism. For the past decade, it was considered a disorder of fatty acid metabolism, because free fatty acids (FFAs) circulate in high levels in obesity and promote insulin resistance and hepatic glucose production. 6 Recently, increasing evidence indicates that abnormalities in adipokine secretion from fat and in mitochondrial metabolism play a central role in the pathogenesis of this disease. 7,8 Insulin resistance, defined as a defect in the ability of insulin to drive glucose into its major target tissue, skeletal muscle, 9 is a key factor in the pathogenesis of type 2 diabetes and a cofactor in the development of dyslipidemia, hypertension, and atherosclerosis. 10 Insulin resistance is present in Ͼ90% of people with type 2 diabetes and predates the development of hyperglycemia by many years. 11 In the early states, insulin resistance is ...