Association of adipokines with insulin resistance and metabolic syndrome including obesity and diabetes

Adipose tissue (AT) acts as a highly active endocrine organ, which secretes a wide range of adipokine hormones. In the past few years, several adipokines (leptin, adiponectin, resistin etc.) have been discovered showing metabolic consequences in relation to insulin resistance (IR), obesity and diabetes. These adipokines are considered to be an important component playing an important role in the regulation of energy metabolism. They have been shown to be involved in the pathogenesis of metabolic syndrome (MetS) and cardiac diseases. The current article provides a holistic summary of recent knowledge on adipokines and emphasizes their importance in association with IR, obesity, diabetes and MetS. Adipokines such as leptin, adiponectin, resistin and tumor necrosis factor-alpha (TNF-α) have been involved in the regulation of an array of metabolic functions and disease associated with it, e.g. appetite and energy balance of the body, suppression of atherosclerosis and liver fibrosis, obesity with type 2 diabetes (T2D) and IR. An important adipokine, Interleukin-6 (IL-6), also correlates positively with human obesity and IR and also the elevated level of IL-6 predicts development of T2D. All of these hormones have important correlation with energy homeostasis, glucose and lipid metabolism, cardiovascular function and immunity. All the possible connections have extended the biological emphasis of AT secreted adipokines as an investigator in the development of MetS, and are now no longer considered as only an energy storage site.