OBJECTIVE -Hyperinsulinemia is often associated with several metabolic abnormalities and increased blood pressure, which are risk factors for cardiovascular disease. It has been hypothesized that insulin resistance may underlie all these features. However, recent data suggest that some links between insulin resistance and these alterations may be indirect. The aim of our study was to further investigate this issue in a sample of young hyperandrogenic women, who often show insulin resistance and other metabolic abnormalities typical of the insulin resistance syndrome.RESEARCH DESIGN AND METHODS -We tested the hypothesis of a single factor underlying these features by principal component analysis, which should recognize one component if a single mechanism explains this association. The analysis was carried out in a sample of 255 young nondiabetic hyperandrogenic women. Variables selected for this analysis included the basic features of the insulin resistance syndrome and some endocrine parameters related to hyperandrogenism.RESULTS -Principal component analysis identified four separate factors, explaining 64.5% of the total variance in the data: the first included fasting and postchallenge insulin levels, BMI, triglycerides, HDL cholesterol, and uric acid; the second, BMI, blood pressure, and serum free testosterone; the third, fasting plasma glucose, postchallenge glucose and insulin levels, serum triglycerides, and free testosterone; and the fourth, postchallenge plasma insulin, serum free testosterone, and gonadotropin-releasing hormone agonist-stimulated 17-hydroxyprogesterone.CONCLUSIONS -These results support the hypothesis of multiple determinants in the clustering of abnormalities in the so-called insulin resistance syndrome.
Diabetes Care 29:372-378, 2006M any subjects show a clustering of metabolic abnormalities, suggesting that these alterations have shared pathogenetic mechanisms. These abnormalities include hyperglycemia, obesity, dyslipidemia, and hypertension, which are classical risk factors for cardiovascular disease (1-3). As impaired insulin action is a common finding in these subjects, it has been hypothesized that insulin resistance and the associated hyperinsulinemia may be the common link among these alterations. Clustering of these abnormalities has been called insulin resistance syndrome, metabolic syndrome, or syndrome X. According to the working definition recently proposed by the National Cholesterol Education Program Expert Panel (4), prevalence of the metabolic syndrome in the U.S. general population is as high as 20 -25% (5).The high prevalence and the serious implications of this condition indicate the need for an integrated preventive strategy. However, it remains unclear whether insulin resistance directly underlies all these features or whether some links are indirect, being mediated by other factors. A recent report by Meigs et al. (6) supported this latter hypothesis. These authors assessed, by factor analysis, clustering of cardiovascular risk variables in a large cohort of no...
