title: A matter of fat: insulin resistance and oxidative stress.
abstract: BACKGROUND
  Obesity is linked to insulin resistance (IR), which can lead to type 2 diabetes mellitus. Oxidative stress present in early obesity may favor the progression to comorbid conditions.
  
  
  OBJECTIVE
  To examine the relationship between oxidative stress biomarkers and the severity of IR in a group of obese children.
  
  
  METHODS
  Forty obese children with a body mass index (BMI) Z-score ≥ 2 were divided into two groups using the median obtained for the homeostasis model assessment of IR (HOMA-IR). Anthropometric parameters (including body fat composition by bioelectrical impedance) and biochemical parameters were assessed. The following biomarkers of oxidative stress were measured: malondialdehyde (MDA), carbonyl groups (CG), reduced glutathione, oxidized low-density lipoprotein, and vitamin E. Comparisons were adjusted for gender and Tanner stage.
  
  
  RESULTS
  Children with high values of HOMA-IR were more likely to have high body fat percentage and waist circumferences. However, the BMI Z-score did not correlate to the level of IR. Children with higher values of HOMA-IR presented increased levels of markers of oxidative stress in lipids (MDA, p = 0.005) and proteins (CG, p = 0.015). Moreover, MDA increased with increasing levels of HOMA-IR (r = 0.50, p = 0.002), suggesting that lipoperoxidation increases as IR worsens. In a multivariate regression model, only HOMA-IR was predictive of MDA values, irrespective of adiposity parameters and other metabolic risk factors (r2 = 0.22, p = 0.002).
  
  
  CONCLUSIONS
  Oxidative stress increases in obese children according to the severity of IR, which could be linked to the development of comorbidities.
authors.affiliation: Department of Pediatrics, Dr Peset University Hospital, Valencia, Spain. pilar.codoner@uv.es
authors.forename: Pilar
authors.initials: P
authors.lastname: Codoñer-Franch
authors.forename: Almudena
authors.initials: A
authors.lastname: Navarro-Ruiz
authors.forename: María
authors.initials: M
authors.lastname: Fernández-Ferri
authors.forename: Angela
authors.initials: A
authors.lastname: Arilla-Codoñer
authors.forename: Esther
authors.initials: E
authors.lastname: Ballester-Asensio
authors.forename: Victoria
authors.initials: V
authors.lastname: Valls-Bellés
mesh_terms: D000293:Adolescent; D015415:Biomarkers / Q000097:blood; D002648:Child; D003924:Diabetes Mellitus, Type 2 / Q000209:etiology / Q000378:metabolism; D005260:Female; D006706:Homeostasis; D006801:Humans; D007333:Insulin Resistance; D050356:Lipid Metabolism; D008077:Lipoproteins, LDL / Q000097:blood; D008297:Male; D008315:Malondialdehyde / Q000097:blood; D008954:Models, Biological; D009765:Obesity / Q000150:complications* / Q000378:metabolism; D018384:Oxidative Stress
chemical_list: D015415:Biomarkers; D008077:Lipoproteins, LDL; C099252:oxidized low density lipoprotein; D008315:Malondialdehyde