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

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 mid-pubertal adolescents (60 girls & 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 percentiles (normal weight = BMI 95th %tile). Glucose, insulin, adiponectin, resistin, tumor necrosis factor-α, and interleukin-6 were measured, and IR index was based on the Homeostatic Model Assessment (HOMA). Adiponectin, resistin and TNF-α were associated with IR in all adolescents (R2=0.329, p0.050). 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 genders. 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 insulin resistance in adolescents