title: Association between insulin-like growth factor-1, measures of overnutrition and undernutrition and insulin resistance in black adolescents living in the North-West Province, South Africa.
abstract: OBJECTIVE
  To determine if insulin-like growth factor-1 (IGF-1) is a significant predictor of body fat percentage (%BF), lean body mass, and insulin resistance (IR) in black adolescents presenting with overnutrition and undernutrition.
  
  
  METHODS
  A cross-sectional study was undertaken in 181 adolescents (111 girls, 70 boys, 13-20 years old) from a low socio-economic population in the North-West Province, South Africa. Anthropometric measurements were performed, and %BF and lean mass were assessed by air displacement plethysmography. Serum glucose, leptin, insulin, IGF-1 and IGF-binding protein-3 (IGFBP-3) were measured and homeostasis model assessment of IR (HOMA-IR) was calculated. Predictors of body composition and HOMA-IR were determined in multivariate linear regressions.
  
  
  RESULTS
  Of the boys, 31% had a %BF >20%, whereas 42% of girls had a %BF >30%. Furthermore, 17.1% male and 18.9% female adolescents were stunted, indicating overnutrition and undernutrition in the same group. IGF-1 showed a negative association with %BF in both sexes, and a positive correlation with height-for-age z-score (HAZ) and lean mass, respectively, in the boys. IGF-1 correlated positively and physical activity correlated negatively with fasting insulin and HOMA-IR in the girls. In both sexes, leptin had the strongest association with %BF in multiple regressions. Leptin and Tanner stage were significant predictors of HOMA-IR in girls, but not in boys.
  
  
  CONCLUSIONS
  IGF-1 was positively associated with lean mass and HAZ in boys, indicating a beneficial relationship with linear growth, but with IR in the girls, indicating possible adverse metabolic effects in the presence of high %BF and physical inactivity.
authors.affiliation: Centre of Excellence for Nutrition, North-West University, Potchefstroom, 2520, South Africa; Department of Nutrition, University of Venda, Thohoyandou, 0950, South Africa.
authors.forename: Ramoteme L
authors.initials: RL
authors.lastname: Mamabolo
authors.forename: Cristiana
authors.initials: C
authors.lastname: Berti
authors.forename: Makama A
authors.initials: MA
authors.lastname: Monyeki
authors.forename: H Salome
authors.initials: HS
authors.lastname: Kruger
mesh_terms: D050154:Adiposity; D000293:Adolescent; D001823:Body Composition; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D007334:Insulin-Like Growth Factor I / Q000235:genetics* / Q000378:metabolism; D008297:Male; D044342:Malnutrition / Q000453:epidemiology; D044343:Overnutrition / Q000453:epidemiology; D013019:South Africa / Q000453:epidemiology; D055105:Waist Circumference; D055815:Young Adult
chemical_list: D007334:Insulin-Like Growth Factor I