Metabolic syndrome: its history, mechanisms, and limitations.

In late twentieth century, Ruderman and Reaven showed that insulin resistance might be fundamental to metabolic syndrome (MetS) which means a constellation of obesity-related metabolic derangements predisposing to type 2 diabetes and cardiovascular disease. In 2001, user-friendly National Cholesterol Education Program (NCEP) criteria of MetS were proposed. In 2005, the International Diabetes Federation (IDF) and the Examination Committee for Criteria of Metabolic Syndrome in Japan issued different criteria of MetS where abdominal obesity is a necessary component. In 2009, IDF, National Heart, Lung, and Blood Institute, American Heart Association, World Heart Federation, International Atherosclerosis Society, and International Association for the Study of Obesity jointly adopted the revised NCEP criteria, where abdominal obesity is not a necessary component, as worldwide criteria of MetS. In 2010, WHO Expert Consultation warned that MetS is a concept that focuses attention on complex multifactorial health problems but has limited practical utility as a management tool. In animal studies, adipose tissue inflammation characterized by an increased number of crown-like structures in adipose tissue, rather than obesity per se, was shown to be a fundamental mechanism of metabolic derangements.