Persistent increase of prevalence of metabolic syndrome among U.S. adults: NHANES III to NHANES 1999-2006

Adipose tissue dysregulation in patients with metabolic syndrome

CONTEXT

The metabolic syndrome (MetS) is associated with increased risk of diabetes and cardiovascular disease (CVD). Numerous groups have shown increased circulating biomarkers of inflammation in MetS. However, there are scanty data on the cellular sources contributing to this low-grade inflammation.

OBJECTIVE

The aim of this study was to determine the role of sc adipose tissue (SAT) biology in nascent MetS without concomitant diabetes or CVD.

PATIENTS AND METHODS

Subjects with MetS and controls were recruited after informed consent. Fasting blood was collected, and SAT was obtained by biopsy.

RESULTS

Circulating biomarkers of inflammation and insulin resistance, high-sensitivity C-reactive protein (hsCRP), IL-6, IL-1β, leptin, serum amyloid A, and retinol-binding protein-4 (RBP-4) concentrations were significantly higher in the MetS subjects than controls, whereas adiponectin concentrations were lower. In SAT, leptin, RBP-4, CRP, serum amyloid A, plasminogen activator inhibitor-1, IL-1, IL-6, IL-8, and monocyte chemotactic protein-1 (MCP-1) levels were significantly higher in MetS than controls. These differences except for RBP-4 persisted after adjusting for waist circumference. In addition, there were significantly increased numbers of macrophages infiltrating the SAT of MetS and increased numbers of crown-like structures compared with controls. hsCRP correlated positively with homeostasis model assessment and SAT MCP-1 and negatively with adiponectin. Homeostasis model assessment correlated positively with plasminogen activator inhibitor-1, RBP-4, and SAT MCP-1.

CONCLUSIONS

We make the novel observation that SAT of MetS has increased macrophage recruitment with cardinal crown-like structure features and contributes to the increased cellular inflammation that produces increased levels of biomarkers that are correlated with both insulin resistance and low-grade inflammation. These aberrations could contribute to the progression of MetS and the increased risk for diabetes and CVD.

Increasing prevalence of metabolic syndrome in Korea: the Korean National Health and Nutrition Examination Survey for 1998-2007

OBJECTIVE

The number of people with metabolic syndrome is increasing worldwide, and changes in socioenvironmental factors contribute to this increase. Therefore, investigation of changes in metabolic syndrome and its components in South Korea, where rapid socioenvironmental changes have occurred in recent years, would be foundational in setting up an effective strategy for reducing this increasing trend.

RESEARCH DESIGN AND METHODS

We compared the prevalence and pattern of metabolic syndrome among participants in the Korean National Health and Nutrition Examination Surveys for 1998, 2001, 2005, and 2007. In each survey, stratified, multistage, probability-sampling designs and weighting adjustments were conducted to represent the entire Korean population. The revised National Cholesterol Education Program criteria were used as the definition of metabolic syndrome. All biochemical parameters were measured in a central laboratory.

RESULTS

A total of 6,907 (mean ± SE age 45.0 ± 0.2 years), 4,536 (45.5 ± 0.2), 5,373 (47.1 ± 0.2), and 2,890 (49.9 ± 0.3) Koreans over 20 years of age have participated in the studies in 1998, 2001, 2005, and 2007, respectively. The age-adjusted prevalence of metabolic syndrome increased significantly from 24.9% in 1998, 29.2% in 2001, and 30.4% in 2005 to 31.3% in 2007. Among the five components, the level of low HDL cholesterol increased the most, by 13.8% over the 10 years. Abdominal obesity and hypertriglyceridemia followed, with 8.7 and 4.9% increases, respectively.

CONCLUSIONS

Because dyslipidemia and abdominal obesity were major factors in increasing the prevalence of metabolic syndrome in Koreans for the past 10 years, lifestyle interventions should be conducted at the national level to reduce the burden and consequences of metabolic syndrome.