Insulin resistance and the metabolic syndrome-a challenge of the new millennium.

The term metabolic syndrome is used for describing a cluster of cardiovascular risk factors comprising abdominal obesity, glucose intolerance/type 2 diabetes mellitus, dyslipidaemia and hypertension. A concomitant presentation of all components of the syndrome is rare, therefore, in the view of most experts three out of the four main components are sufficient for defining the syndrome. Another recently identified component of high clinical significance is the impairment of the fibrinolytic system which is now frequently mentioned in extended definitions. This clustering of metabolic risk factors has been described in various combinations and given different names including insulin resistance syndrome or syndrome X. Unfortunately, there is no generally accepted definition so far. The original mentioning of the syndrome goes back to the late sixties, when the metabolic syndrome was described as a 'disorder of genetic adaptation becoming manifest following unrestricted food intake and/or muscular inacitvity'. In its modern meaning this term was propagated by Hanefeld and Leonhardt and by Kaplan, who also called the syndrome the 'deadly quartet' to emphasize its high atherogenic potential.