title: Vitamin D Status, Insulin Resistance, Leptin-To-Adiponectin Ratio in Adolescents: Results of a 1-Year Lifestyle Intervention.
abstract: OBJECTIVE
  We aimed to study the relationships between circulating 25-hydroxyvitamin D [25(OH)D], insulin resistance and leptin-to-adiponectin (L/A) ratio in Guadeloupean children and adolescents and to analyse the changes in 25(OH)D levels after a 1-year lifestyle intervention program.
  
  
  METHODS
  25(OH)D concentrations were measured via a chemiluminescence assay. Cardiometabolic risk factors, homoeostasis model assessment of insulin resistance (HOMA-IR), and adipokines were measured. The lifestyle intervention included dietary counselling, regular physical activity.
  
  
  RESULTS
  Among 117 girls and boys (11-15 years old, 31.6% obese), 40% had vitamin D deficiency (25(OH)D levels < 20 ng/mL). With linear regression models where 25(OH)D and HOMA-IR acted as independent variables and age, sex, BMI, L/A ratio as covariates, 25(OH)D was significantly associated with HOMA-IR alone (P = 0.036). HOMA-IR was also associated with BMI z-score ≥ 2, L/A ratio and an interaction term BMI z-score ≥ 2*L/A ratio (P < 0.001 for all). After one year, in 78 children/adolescent, mean serum 25(OH)D increased significantly from 21.4 ± 4.9 ng/mL at baseline to 23.2 ± 6.0 after 1 year; P = 0.003 whereas BMI z-score, HOMA-IR and L/A ratio decreased significantly (P = 0.003, P < 0.001 and P = 0.012; respectively).
  
  
  CONCLUSIONS
  The association between 25(OH)D and HOMA-IR, independently of obesity and the high prevalence of vitamin D deficiency should be considered in order to prevent the later incidence of T2DM. A healthy lifestyle including non-sedentary and outdoor activities could be a way for improving vitamin D status.
authors.affiliation: Equipe de recherche sur le Risque Cardio métabolique, ECM/LAMIA EA4540, Université des Antilles, Guadeloupe, France.
authors.forename: Christine
authors.initials: C
authors.lastname: Rambhojan
authors.affiliation: Equipe de recherche sur le Risque Cardio métabolique, ECM/LAMIA EA4540, Université des Antilles, Guadeloupe, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Larifla
authors.affiliation: Réseau GRANDIR, Guadeloupe, France.
authors.forename: Josiane
authors.initials: J
authors.lastname: Clepier
authors.affiliation: Sorbonne Université, UPMC Univ Paris 06, UMR_S 1166, ICAN, F-75005, INSERM, UMR_S 1166, ICAN, F-75005; INSERM, UMR_S 1166, ICAN, F-75005; AP-HP, Hôpital Pitié-Salpêtrière-Charles Foix, Biochimie Endocrinienne et Oncologique, F-75651, France.
authors.forename: Elodie
authors.initials: E
authors.lastname: Bouaziz-Amar
authors.affiliation: Equipe de recherche sur le Risque Cardio métabolique, ECM/LAMIA EA4540, Université des Antilles, Guadeloupe, France.
authors.forename: Fritz-Line
authors.initials: FL
authors.lastname: Velayoudom-Cephise
authors.affiliation: Equipe de recherche sur le Risque Cardio métabolique, ECM/LAMIA EA4540, Université des Antilles, Guadeloupe, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Blanchet-Deverly
authors.affiliation: Equipe de recherche sur le Risque Cardio métabolique, ECM/LAMIA EA4540, Université des Antilles, Guadeloupe; Département de Santé Publique, CHU 97159 Pointe-à-Pitre, Guadeloupe, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Armand
authors.affiliation: Centre d'Examens de Santé, AGREXAM, Guadeloupe, France.
authors.forename: Jean
authors.initials: J
authors.lastname: Plumasseau
authors.affiliation: Sorbonne Université, UPMC Univ Paris 06, UMR_S 1166, ICAN, F-75005, INSERM, UMR_S 1166, ICAN, F-75005; INSERM, UMR_S 1166, ICAN, F-75005; AP-HP, Hôpital Pitié-Salpêtrière-Charles Foix, Biochimie Endocrinienne et Oncologique, F-75651, France.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Lacorte
authors.affiliation: CHU de Guadeloupe, Public Health; Equipe de recherche sur le Risque Cardio métabolique, ECM/LAMIA EA4540, Université des Antilles, Guadeloupe, France.
authors.forename: Lydia
authors.initials: L
authors.lastname: Foucan
keywords: Adolescents; Insulin resistance; Leptin-to-adiponectin ratio; Lifestyle intervention; Vitamin D deficiency