Michel Farnier
Point Médical, Dijon, France

The metabolic syndrome (MetS) is a cluster of metabolic abnormalities and risk factors which are associated with increased cardiovascular risk and increased risk for type 2 diabetes. The features of this syndrome include atherogenic dyslipidaemia, impaired glucose regulation and/or insulin-resistance, endothelial dys-function, a pro-inflammatory state, a pro-thrombotic state and elevated blood pressure. Moreover, central accumulation of excess adipose tissue is an important determinant of MetS.

Several organisations have proposed clinical criteria for the identification and diagnosis of MetS. To date, no common definition of the abnormalities, or the thresholds defining an abnormality, has been found for this syndrome. The cornerstone of the WHO definition was that the subjects must have impaired glucose regulation (including diabetes) and/or insulin-resistance. However, insulin-resistance is difficult to quantify in clinical practice. That is why the criteria proposed by the National Cholesterol Education Program Adult Treatment Panel (NCEP ATP) III provide a simpler tool for identifying patients with MetS. The first criterion is abdominal obesity, defined by increased waist circumference. Other criteria are high triglycerides, decreased HDL-cholesterol, elevated blood pressure and high plasma glucose. All these clinical and biological measurements are routinely available.

The NCEP ATP III cut-offs for several of these criteria are not applicable everywhere in the world, and the weight of each criterion may vary from one population to another. Until recently, the prevalence of MetS in France was unknown. The Data from an Epidemiological Study on the Insulin-Resistance syndrome (DESIR) study1 evaluated the frequency of MetS using NCEP ATP III criteria in a French population aged 30 to 64 years old, and the persistence of the syndrome after three years of follow-up. The prevalence of MetS was 9.2% in men and 6.2% in women, compared with 24.0% in men and 23.4% in women in the US NHANES III. Although the DESIR cohort was not strictly representative of the French population, the results concerning the prevalence of the various abnormalities defining the syndrome are likely to be more widespread: using age-standardised frequencies, abdominal obesity was three times less frequent in France than in the US, and low HDL-cholesterol five times less frequent in France than in the US. In contrast, hyper-tension (high blood pressure or presence of an antihypertensive treatment) was roughly two times higher in France than in the US. These findings suggest that different thresholds could be defined for the abnormalities composing MetS in different countries.

The prevalence of MetS appears to be lower in France than in the US, with some specificities in syndrome characteristics. However, the frequency of overweight is increasing in France, particularly among adolescents, and the trends in MetS prevalence in France should be evaluated. As abdominal adiposity is mainly responsible for the rising prevalence of MetS, lifestyle intervention should be the primary target. Encouraging weight reduction and physical activity to control the "obesity epidemic" will be the priority from a public health perspective.

1. Balkau B, Vernay M, Mhamdi L, et al. D.E.S.I.R. Study Group.
The incidence and persistence of the NCEP (National Cholesterol Education Program) metabolic syndrome. The French D.E.S.I.R. study.
Diabetes Metab 2003;29:526-32