Definition and History

The current definition of the metabolic syndrome encompasses a cluster of metabolic abnormalities linked to insulin resistance, which is often associated with a high-risk form of overweight/obesity: excess abdominal obesity. Because these abnormalities increase the risk of cardiovascular disease (CVD) and type 2 diabetes, numerous consensus groups have attempted to provide guidelines to identify patients in clinical practice with these atherogenic/diabetogenic metabolic abnormalities. Although the number of publications on the metabolic syndrome is soaring, the concept of a cluster of abnormalities including obesity, diabetes, dyslipidemia, and hypertension is not new and several physicians/investigators contributed to the development of this concept through astute clinical observations or epidemiological/metabolic studies. However, a clinical diagnosis of the metabolic syndrome is not sufficient to assess the risk of CVD. In order to properly evaluate and manage global CVD risk in clinical practice, it is important to take into account the risk associated with traditional risk factors as well as the potential additional contribution of abdominal obesity/insulin resistance and related complications. This global risk is referred to as global cardiometabolic risk.

Obesity and insulin resistance have been linked to a series of complications for over 40 years. The metabolic syndrome refers to a cluster of metabolic abnormalities caused by insulin resistance, which is often associated with a high-risk form of overweight/obesity: visceral obesity. Because these abnormalities increase the risk of cardiovascular disease (CVD) and type 2 diabetes, numerous consensus groups have proposed clinical tools to identify individuals with these atherogenic and diabetogenic metabolic complications. The debate continues as to whether features of the metabolic syndrome increase CVD risk beyond the risk posed by traditional CVD risk factors. This debate has spurred the creation of a new concept: global cardiometabolic risk (CMR). CMR encompasses overall CVD risk resulting from traditional risk factors (age, sex, smoking, hypertension, LDL cholesterol, HDL cholesterol, diabetes) and from the additional risks of visceral obesity and related features of the metabolic syndrome.

For more detailed information on the history of the metabolic syndrome and on global cardiometabolic risk, the reader is invited to consult several review papers [1-4].