Adipose tissue is not simply a store of excess energy, but also secretes a variety of proteins into circulating blood that influence systemic metabolism. These include tumor necrosis factor (TNF-alpha), plasminogen activator inhibitor type 1 (PAI-1), leptin, resistine and adiponectin. These are collectively known as adipocytokines. Adiponectin (also referred to as AdipoQ, Acrp 30, apM1 or GBP28) is a novel adipose-specific protein. A recent genome study mapped a susceptibility locus for type 2 diabetes and the metabolic syndrome on chromosome 3q27, where the adiponectin gene is located. Adiponectin is a peculiar adipocytokine because in contrast to the markedly increased levels of many others, as leptin or TNF-alpha, its level is reduced in obesity and type 2 diabetes. The administration of thiazolidinediones, which are synthetic PPARs-gamma ligands, significantly increases the plasma adiponectin concentrations, an effect that could improve insulin sensitivity. Thus, the administration of adiponectin may provide a novel treatment modality for insulin resistance and type 2 diabetes.