Chapter 4 - Adiponectin: A Mediator of Obesity, Insulin Resistance, Diabetes, and the Metabolic Syndrome

Abstract

The worldwide prevalence of obesity has nearly doubled since 1980. More than 42 million children under the age of 5 years were overweight in 2013 according to the World Health Organization’s 2014 global status report on noncommunicable diseases. In 2014, 11% of men and 15% of women aged 18 years and older were obese. Obesity increases the risk of developing insulin resistance, type 2 diabetes, dyslipidemia, hypertension, and atherosclerosis, and the coexistence of these diseases has been termed the metabolic syndrome. Once regarded as a relatively inert storage depot for fat, the adipose tissue is now recognized as an important endocrine organ that releases a host of biologically active hormones and cytokines collectively referred to as adipokines. Adiponectin, an adipokine, has emerged as a major player in the pathogenesis of obesity, insulin resistance, and metabolic syndrome. Emerging evidence also indicates the association of obesity and insulin resistance with a state of low-grade chronic inflammation of the adipose tissue as a result of incessant activation of the native immune system which plays a major role in the pathogenesis of obesity-related metabolic complications. These developments have contributed considerably to an improved understanding of the cellular and molecular mechanisms underlying obesity and insulin resistance.