title: The contribution of SHBG to the variation in HOMA-IR is not dependent on endogenous oestrogen or androgen levels in postmenopausal women.
abstract: OBJECTIVE
  Sex hormone-binding globulin (SHBG) is a robust predictor of insulin resistance. Whether this is independent of circulating sex steroid levels remains uncertain. The aim of this study was to investigate the determinants of SHBG in postmenopausal women and whether the relationship between SHBG and insulin resistance is independent of oestrogen and androgen levels.
  
  
  METHODS
  A cross-sectional study of naturally and surgically menopausal women.
  
  
  METHODS
  Seven hundred and sixty three postmenopausal women not using any systemic hormone therapy, mean age 54·4 ± 5·8 years, recruited in the US, Canada, Australia, UK and Sweden between July 2004 and February 2005.
  
  
  METHODS
  Relationships between log-transformed (ln) SHBG and ln homoeostasis model assessment for insulin resistance (HOMA-IR) were explored, taking into account age, body mass index (BMI), blood pressure (BP) and circulating oestradiol, oestrone, testosterone and dihydrotestosterone.
  
  
  RESULTS
  Taking into account age, race, years since menopause, menopause type, BMI, BP, prior postmenopausal hormone use and the sex steroids measured, 34·4% of the variation in SHBG could be explained by the model that included negative contributions by HOMA-IR, BMI and diastolic BP, and a positive contribution by total testosterone (P < 0·001). None of the sex steroids made independent contributions to HOMA-IR, which was best explained by the model that included BMI, SHBG, systolic BP and surgical menopause, with each variable being positively related to HOMA-IR (r(2) = 0·3152, P = 0·03).
  
  
  CONCLUSIONS
  The relationship between SHBG and HOMA-IR, as an estimate of insulin resistance, is not explained by endogenous oestrogen and androgen levels and is, at least in part, independent of BMI in postmenopausal women.
authors: Women's Health Research Program, School of Public Health and Preventive Medicine, Monash University, Melbourne, Vic., Australia. susan.davis@monash.edu
authors: Susan R
authors: SR
authors: Davis
authors: Penelope J
authors: PJ
authors: Robinson
authors: Alain
authors: A
authors: Moufarege
authors: Robin J
authors: RJ
authors: Bell
mesh_terms: D000328:Adult; D000368:Aged; D000728:Androgens / Q000097:blood*; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D004958:Estradiol / Q000097:blood; D004967:Estrogens / Q000097:blood*; D005260:Female; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D008875:Middle Aged; D017698:Postmenopause / Q000097:blood* / Q000378:metabolism*; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism*; D013739:Testosterone / Q000097:blood; D055815:Young Adult
chemical_list: D000728:Androgens; D004967:Estrogens; D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D004958:Estradiol