Adipose tissue, in addition to the storage of lipids function for lipids, plays active roles in normal metabolic homeostasis and in the development of several diseases, such as type 2 diabetes, dyslipaemia and atherosclerosis. These roles are mediated by adipocytokines, factors secreted by adipose tissue. These include tumor necrosis factors (TNF)-alpha, leptin, resistin, adiponectin or visfatin. Adipocytokines act in an autocrine, paracrine and endocrine manner. Adiponectin is a peculiar adipocytokine because in contrast to the markedly increased levels of leptin, resistin or TNF-alpha in obesity, its level is negatively correlated with body mass index, and is decreased in presence of insulin resistance and in type 2 diabetes. Adiponectin may play a crucial role in the development of diabetes mellitus and high adiponectin levels should protect against impairment of glucose metabolism. Moreover, adipocytokines are involved in the pathogenesis of vascular diseases and may represent a link between obesity, diabetes, inflammation and atherosclerosis. Weight loss, exercise and some antidiabetic drugs also influence plasma adipocytokines levels. For instance, thiazolidinediones treatment in patients with type 2 diabetes resulted in an increased in plasma adiponectin levels and a decrease in circulating TNF-alpha concentrations.