The association between insulin resistance and cytokines in adolescents: the role of weight status and exercise

Rubin, Daniela A.; McMurray, Robert G.; Harrell, Joanne S.; Hackney, Anthony C.; Thorpe, Deborah E.; Haqq, Andrea M.

doi:10.1016/j.metabol.2008.01.005

« Previous Next »Metabolism - Clinical and Experimental
Volume 57, Issue 5 , Pages 683-690, May 2008

The association between insulin resistance and cytokines in adolescents: the role of weight status and exercise

Daniela A. Rubin
- Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- School of Medicine, Department of Allied Health Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Department of Kinesiology, California State University Fullerton, Fullerton, CA 92834, USA
- Corresponding author. Department of Kinesiology, KHS 138, California State University Fullerton, Fullerton, CA, 92834-3599, USA. Tel.: +1 714 278 4704; fax: +1 714 278 5317.
Robert G. McMurray
- Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- School of Medicine, Department of Allied Health Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
Joanne S. Harrell
- School of Nursing, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
Anthony C. Hackney
- Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- School of Medicine, Department of Allied Health Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
Deborah E. Thorpe
- School of Medicine, Department of Allied Health Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
Andrea M. Haqq
- Department of Pediatrics, Duke University Medical Center, Durham, NC 27710, USA

Received 9 April 2007; accepted 7 January 2008.

Abstract

Increased adiposity is associated with insulin resistance (IR) and an inflammatory response in adults. We tested the hypotheses that cytokines associated with adiposity are also correlated with IR in early adolescents and that these relationships are moderated by weight status, levels of vigorous physical activity (VPA), or maximal aerobic power (pVO₂max). Body mass, stature, and a fasting blood sample were obtained from 120 midpubertal adolescents (60 girls and 60 boys). Habitual VPA was obtained by a survey. Predicted VO₂max was determined using a cycle ergometer test. Weight status was based on body mass index (BMI) percentiles (normal weight = BMI <75th percentile, overweight = BMI >95th percentile). Glucose, insulin, adiponectin, resistin, tumor necrosis factor–α (TNF-α), and interleukin-6 were measured; and IR index was based on the Homeostatic Model Assessment. Adiponectin, resistin, and TNF-α were associated with IR in all adolescents (R² = 0.329, P < .001; R² = 0.152, P = .001; and R² = 0.141, P = .002; respectively); but interleukin-6 was not (R² = 0.148, P = .114). The degree of association between adiponectin and IR was stronger in overweight than in normal-weight adolescents (P < .050). When regression models included weight status, neither TNF-α nor resistin was significantly related to IR (P > .050). Exercise did not moderate the association between these cytokines and IR. However, higher levels of VPA and/or pVO₂max were associated with higher adiponectin, lower resistin, and lower TNF-α in at least one of the sexes. Our results indicate that the pathophysiology of obesity is already established in early adolescents. Increased adiposity, resulting in reduced adiponectin and increased resistin and TNF-α, may link these cytokines with IR in adolescents.