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Background: The metabolic syndrome is a constellation of risk factors including dyslipidemia, dysglycemia, hypertension, a pro-inflammatory state, and a prothrombotic state. All of these factors are accentuated by obesity. However, obesity can be defined by body mass index (BMI), percent body fat, or by body fat distribution. The latter consists of upper body fat (subcutaneous and visceral fat) and lower body fat (gluteofemoral fat). Waist circumference is a common surrogate marker for upper body fat., Methods: Data from the National Health and Nutrition Examination Survey (NHANES) for the years 1999-2006 was examined for associations of metabolic risk factors with percent body fat, waist circumference, and BMI., Results: Associations between absolute measures of waist circumference and risk factors were similiar for men and women. The similarities of associations between waist circumference and risk factors suggests that greater visceral fat in men does not accentuate the influence of upper body fat on risk factors., Conclusions: Different waist concumference values should not be used to define abdominal obesity in men and women., (© 2018 The Authors. European Journal of Clinical Investigation published by John Wiley & Sons Ltd on behalf of Stichting European Society for Clinical Investigation Journal Foundation.)

Objective: Visceral (VAT) and abdominal subcutaneous (SAT) adipose tissues contribute to obesity but may have different metabolic and atherosclerosis risk profiles. We sought to determine the associations of abdominal VAT and SAT mass with markers of cardiac and metabolic risk in a large, multiethnic, population-based cohort of obese adults., Design and Methods: Among obese participants in the Dallas Heart Study, we examined the cross-sectional associations of abdominal VAT and SAT mass, assessed by magnetic resonance imaging (MRI) and indexed to body surface area (BSA), with circulating biomarkers of insulin resistance, dyslipidemia, and inflammation (n = 942); and with aortic plaque and liver fat by MRI and coronary calcium by computed tomography (n = 1200). Associations of VAT/BSA and SAT/BSA were examined after adjustment for age, sex, race, menopause, and body mass index., Results: In multivariable models, VAT significantly associated with the homeostasis model assessment of insulin resistance (HOMA-IR), lower adiponectin, smaller LDL and HDL particle size, larger VLDL size, and increased LDL and VLDL particle number (p < 0.001 for each). VAT also associated with prevalent diabetes, metabolic syndrome, hepatic steatosis, and aortic plaque (p < 0.001 for each). VAT independently associated with C-reactive protein but not with any other inflammatory biomarkers tested. In contrast, SAT associated with leptin and inflammatory biomarkers, but not with dyslipidemia or atherosclerosis. Associations between SAT and HOMA-IR were significant in univariable analyses but attenuated after multivariable adjustment., Conclusion: VAT associated with an adverse metabolic, dyslipidemic, and atherogenic obesity phenotype. In contrast, SAT demonstrated a more benign phenotype, characterized by modest associations with inflammatory biomarkers and leptin, but no independent association with dyslipidemia, insulin resistance, or atherosclerosis in obese individuals. These findings suggest that abdominal fat distribution defines distinct obesity sub-phenotypes with heterogeneous metabolic and atherosclerosis risk., (Copyright © 2012 The Obesity Society.)

Diabetes mellitus (DM) has been termed a "coronary disease equivalent", yet data suggest that only those DM subjects with metabolic syndrome (MetS) are at increased coronary risk. Using data from the Dallas Heart Study, a large, probability-based population study, we assessed the individual and joint associations between MetS, DM and atherosclerosis, defined as coronary artery calcium (CAC) detected by electron-beam computerised tomography (EBCT) and abdominal aortic plaque (AAP) detected by magnetic resonance imaging. Among 2,735 participants, the median age was 44 years; 1,863 (68%) were non-white; 1,509 (55%) were women; 697 (25.5%) had MetS without DM; 53 (1.9%) had DM without MetS; and 246 (9.0%) had both DM and MetS. The prevalence of CAC increased from those with neither MetS nor DM (16.6%) to MetS only (24.0%) to DM only (30.2%) to both MetS and DM (44.7%) (ptrend <0.0001). The prevalence of CAC was higher in those with both DM and MetS versus either alone (p<0.0001). After adjustment, MetS and DM were each independently associated with CAC (odds ratio [OR] 1.4, 95% confidence intervals [CI] 1.1-1.8; OR 1.8, 95% CI 1.3-2.5, respectively). Compared with the group without DM or MetS, those with both MetS and DM had the most CAC (adjusted OR 2.3; 95% CI 1.6-3.2). All analyses of AAP yielded qualitatively similar results. In conclusion, both MetS and DM are independently associated with an increased prevalence of atherosclerosis, with the highest observed prevalence in subjects with both DM and MetS.

Objective: Although IL-18 promotes atherogenesis in animal studies and predicts cardiovascular risk in humans, it is unknown whether elevated IL-18 levels are associated with coronary atherosclerosis in the general population., Methods and Results: IL-18 plasma levels were determined by ELISA in 2231 subjects from the Dallas Heart Study. In univariable analysis, IL-18 levels associated with traditional cardiovascular risk factors and particularly with components of the metabolic syndrome (MS, P<0.01 for trend across the number of MS components); IL-18 also associated with coronary artery calcium (CAC) scores measured by electron beam computed tomography and aortic plaque measured by MRI (P<0.01 for each). In multivariable analyses, IL-18 remained associated with multiple components of the MS but not with CAC or aortic plaque., Conclusions: In a large population-based sample, elevated IL-18 plasma levels associated with risk factors for atherosclerosis and with the metabolic syndrome. The association between IL-18 and atherosclerosis diminished after accounting for traditional cardiovascular risk factors. These data suggest that IL-18 does not add independently to detection of atherosclerotic burden in asymptomatic individuals.