title: Limitations of fasting indices in the measurement of insulin sensitivity in Afro-Caribbean adults.
abstract: BACKGROUND
  Insulin sensitivity can be estimated using glucose disposal rate (M) measured during a hyperinsulinemic euglycemic clamp (HEC) or insulin sensitivity index (SI) derived from a frequently sampled intravenous glucose tolerance test (FSIVGTT). The commonly used homeostatic model assessment of insulin resistance (HOMA-IR) which utilizes fasting glucose and insulin has been validated against M across several populations (r = 0.5-0.8). This study sought to validate HOMA-IR against SI and M in an Afro-Caribbean population.
  
  
  RESULTS
  Sixty participants completed a 180-minute FSIVGTT and another 50 completed a 150-minute hyperinsulinemic euglycemic clamp. In both groups, HOMA-IR was calculated and anthropometry and body composition using dual energy x-ray absorptiometry (DEXA) were measured.FSIVGTT: The participants were 55% male, age 23.1 ± 0.05 years, BMI 24.8 ± 6.3 kg/m2 and % body fat 25.0 ± 15.2 (mean ± SD). HEC: The participants were 44% male, age 27.3 ± 8.1 years, BMI 23.6 ± 5.0 kg/m2 and % body fat 24.7 ± 14.2 (mean ± SD). While HOMA-IR, SI and M correlated with waist, BMI and % body fat (P-values < 0.01) there were no significant correlations between HOMA-IR with either SI or M-value (P-values > 0.2).
  
  
  CONCLUSIONS
  In young Afro-Caribbean adults, HOMA-IR compared poorly with other measures of insulin sensitivity. It remains important to determine whether similar findings occur in a more insulin resistant population. However, HOMA-IR correlated with clinical measures of insulin sensitivity (i.e. adiposity), so it may still be useful in epidemiological studies.
authors.affiliation: Tropical Medicine Research Institute, The University of the West Indies, Mona, Kingston 7, Jamaica. debbie.thompson@uwimona.edu.jm.
authors.forename: Debbie S
authors.initials: DS
authors.lastname: Thompson
authors.forename: Michael S
authors.initials: MS
authors.lastname: Boyne
authors.forename: Clive
authors.initials: C
authors.lastname: Osmond
authors.forename: Trevor S
authors.initials: TS
authors.lastname: Ferguson
authors.forename: Marshall K
authors.initials: MK
authors.lastname: Tulloch-Reid
authors.forename: Rainford J
authors.initials: RJ
authors.lastname: Wilks
authors.forename: Alan T
authors.initials: AT
authors.lastname: Barnett
authors.forename: Terrence E
authors.initials: TE
authors.lastname: Forrester
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D044383:Black People; D001786:Blood Glucose / Q000378:metabolism; D001823:Body Composition; D015992:Body Mass Index; D005215:Fasting / Q000097:blood*; D005260:Female; D015309:Glucose Clamp Technique / Q000379:methods*; D005951:Glucose Tolerance Test / Q000379:methods*; D006801:Humans; D006946:Hyperinsulinism / Q000097:blood; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000208:ethnology*; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014900:West Indies; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D007328:Insulin