Fasting serum insulin in relation to components of the metabolic syndrome in European healthy men: the European Fat Distribution Study

To investigate the "metabolic" syndrome in different European populations, samples of 38-year-old healthy men were randomly selected from six centers: Gothenburg (Sweden), Warsaw (Poland), Deinze (Belgium), Verona (Italy), Lumiar (Portugal), and Ede (The Netherlands). In total, 515 men were studied. Anthropometric measurements and blood pressure levels were taken by one or two operators in each center after a common operator's training course. Each blood parameter was analyzed in one laboratory. There were significant intercenter differences in mean values for anthropometric parameters, blood pressure, serum lipids (except for low-density lipoprotein [LDL] cholesterol), and fasting insulin. In particular, fasting serum insulin showed the highest values in Sweden and The Netherlands and the lowest values in Italy and Portugal. In pooled men, fasting insulin was strongly related (P < .001) to body mass index (BMI), waist to hip (WHR) and waist to thigh (WTR) circumference ratios, serum lipids (except for LDL cholesterol), and blood pressure. On the contrary, there were relevant differences in the correlation of insulin with serum lipids and blood pressure when the data were evaluated for each center. However, generally both in each center and in all centers together all these correlations disappeared after adjustment for BMI, with the exception of the correlation with serum triglycerides. In pooled men, multiple regression analysis showed an independent association of fasting insulin, BMI, and WHR with serum triglyceride (P < .001). On the contrary, total, LDL, and high-density lipoprotein (HDL) cholesterol and blood pressure values showed independent associations with BMI and/or WHR but not with fasting insulin in multivariate models.2+ off