The liver in metabolic syndrome

The liver plays a major role in the regulation of pathways that govern systemic metabolic homeostasis. Hepatic regulation of glucose and lipid homeostasis is under the control of a complex system of hormones, transcription factors, and signaling pathways. Hepatic steatosis is a condition characterized by an increased amount of fat in the liver, mainly in the form of triglycerides, in a quantity greater than 5% of liver weight, or histologically defined when 5% or more of hepatocytes contains visible intracellular triglycerides, that cannot be attributed to alcohol consumption. Fatty liver is closely related to impairment in glucose, fatty acid, and lipoprotein metabolism, and it is now widely recognized as the hepatic manifestation of the Metabolic Syndrome. In the present chapter we will critically present the potential mechanisms that link obesity, type 2 diabetes, hepatic lipid accumulation, and insulin resistance. Indeed, although the correlation between fatty liver and insulin resistance is well established, we will specifically discuss the combination of elevated serum levels of glucose, fatty acids, and peripheral insulin resistance for the pathogenesis of liver dysfunction in the Metabolic Syndrome.