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

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 (pVO 2 max). 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 VO 2 max was determined using a cycle-ergometer test. Weight status was based on body mass index percentiles (normal weight = BMI < 75 th %tile and overweight = 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 (R 2 =0.329, p<0.001, R 2 =0.152, p=0.001, R 2 =0.141, p=0.002; respectively), but IL-6 was not (R 2 =0.148, p=0.114). The degree of association between adiponectin and IR was stronger in overweight than in normal weight adolescents (p<0.050). When regression models included weight status, neither TNF-α nor resistin were significantly related to IR (p>0.050). Exercise did not moderate the association between these cytokines and IR. However, higher levels of VPA and/or pVO 2 max 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.

Relação entre tecido adiposo e osso: associações entre vitamina D, osteocalcina, adipocinas e homeostase da glicose em crianças e adolescentes

“…In spite of the usual positive correlation between low physical activity level and obesity 52 and risk for diabetes observed by others 53 , our results do not show an association between physical activity and nutritional status, insulin resistance or β-cell function. On the other hand, adiponectin/leptin ratio, a good parameter for disturbances on glucose homeostasis and adiposity 22,24 , was shown to be higher among active and very active adolescents, compared to sedentary and insufficiently active subjects.…”

Associations of Physical Activity With Inflammatory Factors, Adipocytokines, and Metabolic Syndrome in Middle-Aged and Older Chinese People

“…18 In a crosssectional analysis including 120 adolescents, higher levels of vigorous-intensity activity were associated with higher adiponectin levels. 19 A study in 60 white men and women found that RBP4 was significantly decreased in those with improved insulin sensitivity after 1 month of exercise training. 5 Similarly, in obese children, RBP4 levels were reduced remarkably after a 3-month physical activity-based lifestyle intervention.…”

Circulating proinflammatory peptides related to abdominal adiposity and cardiometabolic risk factors in healthy prepubertal children

“…A number of studies have investigated the relationship between the circulating levels of adipokines, anthropometric indices and cardiometabolic risk factors in obese children and adolescents (10,11). However, the majority of these have been limited mainly to associations between crude measures of adiposity such as body mass index (BMI) and CRP as a marker for an increased risk of coronary artery disease (12,13), reporting age diversity of the participants (14,15) or inconsistent results (16,17). Less is known about the presence of low-grade systemic inflammation in healthy children with central obesity and on its potential associations with various cardiometabolic alterations before the onset of puberty (18,19).…”