Trends in Metabolic Syndrome
According to a Gallup-Healthways survey, the number of obese adults in the U.S. increased in 2013 to 27.1%, up from 26.2% in 2012 and 25.5% in 2008.  However, the prevalence of metabolic syndrome, a serious health condition defined by a combination of cardiovascular risk factors including insulin resistance, central obesity, hypertension, and artherogenic dyslipidemia, has actually decreased in adults, from 25.5% in 1999-2000 to 22.9% in 2009-2010.[2,3] While fewer Americans are meeting the criteria for metabolic syndrome, certain components of the syndrome continue to increase. For example, waistlines, particularly in women, continue to expand, and the prevalence of hyperglycemia has increased by 54% over the past 10 years.
A recent study analyzed data from the National Health and Nutrition Examination Survey (NHANES) from 1999-2000 through 2009-2010 to evaluate prevalence trends for metabolic syndrome and its individual components. The study also compared time trends in risk factors by sex and across racial/ethnic groups. The study sample consisted of 10,814 NHANES participants with complete data on the parameters that make up metabolic syndrome. The decline in age-adjusted prevalence of metabolic syndrome across the six cycles achieved statistical significance with a pvalue of 0.024. Overall, three of the five components of metabolic syndrome declined in prevalence and two increased. Decreases were elevated blood pressure (from 32.3% to 24.0%), hypertriglyceridemia (from 33.5% to 24.3%), and low HDL (from 38.5% to 30.1%). Abdominal obesity increased from 45.4% to 56.1% and hyperglycemia increased from 12.9% to 19.9%.
Metabolic syndrome prevalence decline was greatest in non-Mexican-American whites, from 25.59% to 21.77%. In non-Mexican-American blacks and Mexican Americans rates remained the same. Waist circumference increased significantly in both whites and blacks, but not in Mexican Americans. Rates of elevated blood pressure decreased in all three ethnic groups, and hypertriglyceridemia prevalence declined significantly in whites and increased slightly in blacks. Low-HDL occurred significantly less in all three groups, with the largest decrease in whites. There was an increased use of lipid-modifying agents, which is associated with the decline of dyslipidemia. Prevalence of fasting hyperglycemia increased significantly in all three groups, with the greatest increase in Mexican Americans.
This study revealed potential targets for interventions that will reduce the future burden of cardiovascular disease and type 2 diabetes because these two components of metabolic syndrome have an independent association. It also confirms the dire need for coordinated treatment programs to combat the increasing prevalence of obesity.