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The metabolic syndrome (MS) described as a link between
insulin resistance, hypertension, dyslipidemia, and type 2 diabetes mellitus
(T2DM), with an increased risk of atherosclerotic cardiovascular disease, has
been reported to have a prevalence of 6.8% among overweight adolescents and
28.7% among obese adolescents (NHANES III). In order to determine the effect of
the degree of obesity on the prevalence of the MS and its relationship to
insulin resistance, Weiss and colleagues studied 439 obese (BMI >97% for age
and sex), 31 overweight (BMI 85%–97% for age and sex), and 20 non-obese
children and adolescents (4–20 years of age) with baseline measurements of BMI,
blood pressure (BP), plasma lipids, C-reactive protein, interleukin-6, and
adiponectin. Oral glucose tolerance tests were performed as well. Degree of
obesity was defined by BMI z-scores (moderately obese = 2.0–2.5 and severely
obese >2.5). The overall prevalence of MS was 38.7% in moderately obese
subjects and 49.7% in severely obese subjects. Glucose, insulin, insulin
resistance, triglycerides, C-reactive protein, interleukin-6, systolic BP, and
prevalence of glucose intolerance (defined as 2hr glucose of 140–200 mg/dL)
increased with increasing obesity. HDL cholesterol and adiponectin decreased
with increasing adiposity. Three factors explained 58% of the variance
observed: obesity and glucose metabolism, dyslipidemia and BP. Through multiple
regression analysis of risk factors associated with the syndrome, a significant
risk included age, sex, BMI z-score, race or ethnic group, and insulin
resistance. Each half-unit increase in the BMI z-score was associated with a
significant increase in the risk of the MS. White children had a higher risk
than black children, and girls had a lower risk than boys.
A 2-year follow-up study
was performed in 77 children; 34 with and 43 without MS. At follow-up 24 of 34
children continued to have MS. The 10 who improved had a lower BMI initially,
gained less weight over the 2 years, and had decreased insulin resistance. The
MS developed in 16 of 43 children who did not meet the criteria at baseline;
they had gained more weight than the others. Eight subjects developed T2DM, and
all had impaired glucose tolerance at baseline. The authors conclude that MS is
much more common than previously reported and that each element of the syndrome
is adversely affected by increasing weight. Of particular concern were the
markers of inflammation, interleukin-6 and C-reactive protein, which escalated
with increasing obesity and presumably put these children at high risk for
cardiovascular disease.
Weiss R, Dziura J, Burgert TS, et al. Obesity and the metabolic syndrome in children and adolescents. N Engl J Med. 2004;350:2362–2374.
Editor's Comment: This manuscript presents some frightening data.
The prevalence of MS, once a diagnosis reserved almost exclusively for adults,
is very common among obese adolescents. Weiss et al showed that not only
adolescents, but children meet the criteria for this diagnosis, and that
markers of cardiovascular inflammation are present at a very young age. The
progression to develop MS over 2 years as weight continues to increase is
remarkable.
Despite the
importance of the documentation that this manuscript presents, the findings and
conclusions are not surprising to most physicians who provide care to America’s young. Indeed, the epidemic of childhood obesity is evident to any observer of
children. It is heartening that some federal research funds are now being made
available to study this problem and that Medicare is beginning to recognize
obesity as a medical condition. Regardless of the data documenting the
prevalence of obesity and the morbidities and co-morbidities associated with
it, the behavioral and societal interventions required to stop its progression
have not been adequately addressed. Reduction in the incidence and severity of
obesity will require more than medical research—it will require significant
input of pediatricians and family physicians, schools, media, and commercial
enterprises. Being apprised of the seriousness of the problem is just another
wake-up call.
William L. Clarke, MD
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Current GGH - Vol. 24 No. 1
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