Does the metabolic syndrome exist? The identification of cardio-metabolic profiles in a South Asian population study

OBJECTIVE Research testing the validity of the metabolic syndrome (MetS) as a clinical construct associated with cardiovascular disease risk has produced inconsistent results. This study tested the existence of the MetS, explored alternative cardiometabolic risk characterisations, and examined the relative influence of genetic and environmental factors in a South Asian sample. RESEARCH DESIGN AND METHODS Data came from the Colombo Twin and Singleton follow-up Study, CoTaSS-2 (N=3969). Latent class analysis tested the clustering of MetS indicators (waist circumference, high-density-lipoprotein cholesterol (HDL-C), triglycerides (TG), blood pressure, fasting plasma glucose (FPG), medications and diabetes). Regression analyses tested cross-sectional associations between identified latent classes and covariates. Structural equation modelling estimated genetic and environmental influences on these classes. Analyses were stratified by gender (n=1681 men, n=2288 women). RESULTS Three classes were identified in men: 1) “Healthy” (52.3%), 2) “Central obesity, high TG, high FPG” (40.2%), and 3) “Central obesity, high TG, diabetes” (7.6%). Four classes were identified in women: 1) “Healthy” (53.2%), 2) “Very high central obesity, low HDL-C, raised FPG” (32.8%), 3) “Very high central obesity, diabetes” (7.2%) and 4) “Central obesity, hypertension, raised FPG” (6.8%). Older age in men and women, and high socioeconomic status in men, was associated with cardiometabolic risk categories, compared to the “Healthy” classes. In men, individual differences in cardiometabolic class membership were due to environmental effects. In females, genetic differences significantly predicted class membership. CONCLUSIONS The findings did not support the MetS construct. Instead, distinct clinical profiles were identified in men and women, suggesting different aetiological pathways.