Comparison of different definitions of pediatric metabolic syndrome: relation to abdominal adiposity, insulin resistance, adiponectin, and inflammatory biomarkers.

OBJECTIVES: To examine the prevalence of the metabolic syndrome using different pediatric definitions reported in the literature and its relationship to abdominal adipose tissue (AT), in vivo insulin resistance, and inflammatory biomarkers in children and adolescents, as well as the utility of fasting insulin and adiponectin as predictors of the metabolic syndrome. STUDY
DESIGN: Cross-sectional measurements were obtained from 122 African Americans and 129 Caucasians age 8 to 19 years. Insulin sensitivity (IS) was measured by a 3-h hyperinsulinemic-euglycemic clamp. Blood pressure, fasting lipids, adiponectin, interleukin (IL)-6, adhesion molecules (intercellular adhesion molecule [ICAM]-1, vascular cell adhesion molecule [VCAM]-1, and E-selectin), and abdominal AT were measured.
RESULTS: Regardless of the metabolic syndrome criteria used, the prevalence of the metabolic syndrome was higher in overweight (24% approximately 51%) compared with non-overweight youths (1% approximately 3%) in both African Americans and Caucasians (P <.01). Youths with the metabolic syndrome had higher visceral AT and fasting insulin and lower IS and adiponetin independent of race (P < .01). In Caucasians, youths with the metabolic syndrome had higher levels of inflammatory biomarkers (IL-6, ICAM-1, and E-selectin). The area under the receiver operating curve (AUC) for insulin was 0.86 approximately 0.89 in African Americans and 0.86 approximately 0.89 in Caucasians, depending on the metabolic syndrome criteria used. For adiponetin, the AUC was 0.73 approximately 0.78 in African Americans and 0.81 approximately 0.86 in Caucasians.
CONCLUSIONS: The prevalence of metabolic syndrome varies depending on the definition used in the literature. Thus, there is a need for a unified definition of this syndrome in children and adolescents to streamline the research in this area. Independent of race, visceral obesity, insulin resistance, hyperinsulinemia, and hypoadiponectinemia are the common characteristics of youths with the metabolic syndrome. In Caucasians but not in African Americans, the metabolic syndrome is associated with increased inflammatory markers; however, the translation of such findings remains to be determined based on long-term longitudinal outcome studies in different racial groups.