Introduction: Childhood obesity and insulin resistance (IR) are rising in prevalence, increasing the future adults' cardio-metabolic risk. One of the potential mechanisms behind these alterations is oxidative stress, fruit of increased free radical production and diminished antioxidant defense. Although low plasma vitamin concentrations and oxidative stress have been observed to be associated with obesity in adults and children, their association with IR in children is less clear.
Materials and Methods: 985 children (49.2% males, 71.7% prepubertal, 24.8% overweight, 47.1% obesity) were recruited for this study. Pubertal status was assessed and anthropometry (weight, height), systolic and diastolic blood pressure (SBP, DBP) and serum glucose, insulin, triacylglycerols (TAG) and high-density lipoprotein cholesterol (HDL-C) were measured. Plasma concentrations tocopherols and carotenes were determined with ultra-high-pressure liquid chromatography coupled to mass spectrometry and concentrations were referred to TAG. Glucose ≥100 mg/dL was considered hyperglycemia whereas HOMA-IR≥2.5 in prepubertal males/females, HOMA-IR≥3.38 in pubertal males or HOMA-IR≥3.905 in pubertal females was indicative of IR. General linear models adjusted for sex, age, recruitment center and BMI were used to evaluate differences in vitamin concentrations, and multiple linear regression (including age, sex and BMI) was used to evaluate the independent contribution of plasma tocopherols and carotenes to HOMA-IR values.
Results: Pubertal children with hyperglycemia showed lower tocopherols (0.094±0.041 vs 0.130±0.062, P=0.023) and carotenes (8.21±4.56 vs 14.83±13.25, P=0.012) plasma concentrations than those with normal glycaemia, independently of BMI. Prepubertal and pubertal children with IR showed lower tocopherol (Pre: 0.109±0.044 vs 0.151±0.066, P<0.001; Pub: 0.102±0.041 vs 0.136±0.063, P=0.009) plasma concentrations and prepubertal children with IR showed lower carotenes (10.03±7.68 vs 22.35±19.95, P=0.001) plasma concentrations, both compared with children without IR. Linear regression analyses showed an independent negative association between plasma tocopherols and HOMA-IR values in prepubertal (βest=-0.138, P=0.001) and pubertal (βest=-0.207, P=0.002) children.
Discussion: Our findings agree with previous studies that showed decreased plasma concentrations of tocopherols and carotenes in children with obesity. However, we observe further implications of low circulating concentrations of tocopherols in terms of their negative association with hyperglycemia and insulin resistance in both prepubertal and pubertal children, independently of BMI. These results must be taken into account in the design of prevention and treatment strategies of obesity and its complications in glucose metabolism.
19 Sep 2019 - 21 Sep 2019