The metabolic syndrome is a clustering of risk factors which predispose an 
individual to cardiovascular morbidity and mortality. There is general consensus 
regarding the main components of the syndrome (glucose intolerance, obesity, 
raised blood pressure and dyslipidaemia [elevated triglycerides, low levels of 
high-density lipoprotein cholesterol]) but different definitions require 
different cut points and have different mandatory inclusion criteria. Although 
insulin resistance is considered a major pathological influence, only the World 
Health Organization (WHO) and European Group for the study of Insulin Resistance 
(EGIR) definitions include it amongst the diagnostic criteria and only the 
International Diabetes Federation (IDF) definition has waist circumference as a 
mandatory component. The prevalence of metabolic syndrome within individual 
cohorts varies with the definition used. Within each definition, the prevalence 
of metabolic syndrome increases with age and varies with gender and ethnicity. 
There is a lack of diagnostic concordance between different definitions. Only 
about 30% of people could be given the diagnosis of metabolic syndrome using 
most definitions, and about 3540% of people diagnosed with metabolic syndrome 
are only classified as such using one definition. There is currently debate 
regarding the validity of the term metabolic syndrome, but the presence of one 
cardiovascular risk factor should raise suspicion that additional risk factors 
may also be present and encourage investigation. Individual risk factors should 
be treated.