Serum concentrations of insulin, insulin-like growth factor-I and insulin-like growth factor binding proteins are different between white and African American girls

J Pediatr. 1999 Sep;135(3):296-300. doi: 10.1016/s0022-3476(99)70123-x.


Objectives: To determine whether serum insulin-like growth factor (IGF)-I and IGF binding protein (IGFBP) concentrations are different between African American and white girls.

Study design: Serum glucose and hormone concentrations were measured in blood samples collected after a 12-hour fast from 79 white and 57 African American healthy girls between 9 and 17 years of age. Tanner stages of pubic hair development were evaluated by physical examination, and body composition by dual energy x-ray absorptiometry.

Results: The African American girls were older and sexually more mature and had higher fat mass, higher serum insulin and free IGF-I concentrations, higher serum free IGF-I to total IGF-I ratio, but lower serum IGFBP-1 concentrations than the white girls. After controlling for sexual maturation and fat mass, the serum concentrations of total IGF-I, bound IGF-I, and IGFBP-3 in the white girls became significantly higher than those in the African American girls. The higher concentrations of total IGF-I in the white girls were due to a proportional increase in the concentrations of bound IGF-I that coincided with a similar increase in serum IGFBP-3 concentrations.

Conclusions: Higher serum insulin concentrations in the African American girls are associated with lower serum IGFBP-1 concentrations and increased bioavailability of free IGF-I, which may contribute to their accelerated growth compared with their white counterparts.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Absorptiometry, Photon
  • Adolescent
  • Analysis of Variance
  • Biological Availability
  • Black People / genetics*
  • Blood Glucose / analysis
  • Body Composition / genetics
  • Body Composition / physiology
  • Child
  • Female
  • Growth / genetics
  • Growth / physiology
  • Humans
  • Insulin / blood*
  • Insulin / genetics*
  • Insulin-Like Growth Factor Binding Proteins / blood*
  • Insulin-Like Growth Factor Binding Proteins / genetics*
  • Insulin-Like Growth Factor I / genetics*
  • Insulin-Like Growth Factor I / metabolism*
  • Physical Examination
  • Puberty / genetics
  • Puberty / physiology
  • White People / genetics*


  • Blood Glucose
  • Insulin
  • Insulin-Like Growth Factor Binding Proteins
  • Insulin-Like Growth Factor I