Is waist circumference a better predictor of insulin resistance than body mass index in U.S. adolescents?

Abstract

Purpose: To determine whether waist circumference (WC) is a better predictor of insulin resistance (IR) than body mass index (BMI) in U.S. adolescents aged 12-18 years.

Methods: Using data from the National Health and Nutrition Examination Survey 1999-2002, we evaluated an ethnically diverse sample of 1,571 adolescents with regard to BMI, WC, and fasting glucose and insulin levels. Children were classified as having IR if they had a homeostasis model assessment of insulin resistance (insulin [U/mL] × glucose [mmol/L]/22.5) of greater than 4.39.We created receiver operating characteristic curves predicting IR across various thresholds of WC and BMI, and area under the curve was compared.

Results: The prevalence rate of IR in the study population was 11.8%. Measures of test performance (sensitivity and specificity) for predicting IR were similar for abnormal BMI and WC thresholds; that is, thresholds of BMI 85th% and WC 75th% and thresholds of BMI 95th% and WC 90th% were quite similar. There were no significant differences in area under the curve for WC versus BMI (.85; 95% CI, .83-.88; p = .84) either for the overall population or for specific racial groups.

Conclusions: WC does not seem to provide a distinct advantage over BMI for identifying adolescents with IR.

Conflict of interest statement

Conflict of Interest: There are no competing financial interests in relation to the work described and the authors have nothing to disclose.

Copyright © 2011 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1

Comparison of receiver operator characteristic curves for predicting insulin resistance using body mass index versus waist circumference percentiles (AUC, 95% CI 0.83-0.88 for both) (p=0.84) (n=1571). Dark circles, solid line=body mass index; open circles, dotted line=waist circumference.

Appendix Figure 2

Comparison of receiver operator characteristic curves for predicting insulin resistance using body mass index (AUC 0.90, 95% CI 0.86-0.94) versus waist circumference percentiles (AUC 0.89 (95%CI, 0.85-0.94) for White children (n=428). Dark circles, solid line=body mass index; open circles, dotted line=waist circumference.

Appendix Figure 3

Comparison of receiver operator characteristic curves for predicting insulin resistance using body mass index (AUC 0.82, 95% CI 0.77-0.87) versus waist circumference percentiles (AUC 0.83, 95%CI 0.78-0.88) for Black children (n=439). Dark circles, solid line=body mass index; open circles, dotted line=waist circumference.

Appendix Figure 4

Comparison of receiver operator characteristic curves for predicting insulin resistance using body mass index (AUC 0.84, 95% CI 0.79-0.88) versus waist circumference percentiles (AUC 0.84 (95%CI, 0.80-0.88) for Mexican-American children (n=590). Dark circles, solid line=body mass index; open circles, dotted line=waist circumference.