Adiponectin and leptin in relation to insulin sensitivity.

An increased amount of adipose tissue or its disproportionate distribution between central and peripheral body regions is related to the development of insulin resistance, type 2 diabetes mellitus, dyslipidemia, atherosclerosis, and coronary artery disease. Until recently, adipose tissue was regarded as a storage depot for lipids. It is now viewed as a hormonally active organ that plays a crucial metabolic role. The most important products of adipose tissue collectively referred to as adipocytokines, include adiponectin, leptin, tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), resistin, plasminogen-activating inhibitor-I (PAI-1), and angiotensinogen. These low and medium molecular weight proteins play an important role in the adipose tissue physiology and are believed to be a link between obesity, insulin resistance and endothelial dysfunction. This review describes the metabolic role of two of these proteins, adiponectin and leptin, in relation to insulin sensitivity.