title: Ethnicity-specific obesity cut-points in the development of Type 2 diabetes - a prospective study including three ethnic groups in the United Kingdom.
abstract: OBJECTIVE
  Conventional definitions of obesity, e.g. body mass index (BMI) ≥ 30 kg/m² or waist circumference cut-points of 102 cm (men) and 88 cm (women), may underestimate metabolic risk in non-Europeans. We prospectively identified equivalent ethnicity-specific obesity cut-points for the estimation of diabetes risk in British South Asians, African-Caribbeans and Europeans.
  
  
  METHODS
  We studied a population-based cohort from London, UK (1356 Europeans, 842 South Asians, 335 African-Caribbeans) who were aged 40-69 years at baseline (1988-1991), when they underwent anthropometry, fasting and post-load (75 g oral glucose tolerance test) blood tests. Incident Type 2 diabetes was identified from primary care records, participant recall and/or follow-up biochemistry. Ethnicity-specific obesity cut-points in association with diabetes incidence were estimated using negative binomial regression.
  
  
  RESULTS
  Diabetes incidence rates (per 1000 person years) at a median follow-up of 19 years were 20.8 (95% CI: 18.4, 23.6) and 12.0 (8.3, 17.2) in South Asian men and women, 16.5 (12.7, 21.4) and 17.5 (13.0, 23.7) in African-Caribbean men and women, and 7.4 (6.3, 8.7), and 7.2 (5.3, 9.8) in European men and women. For incidence rates equivalent to those at a BMI of 30 kg/m² in European men and women, age- and sex-adjusted cut-points were: South Asians, 25.2 (23.4, 26.6) kg/m²; and African-Caribbeans, 27.2 (25.2, 28.6) kg/m². For South Asian and African-Caribbean men, respectively, waist circumference cut-points of 90.4 (85.0, 94.5) and 90.6 (85.0, 94.5) cm were equivalent to a value of 102 cm in European men. Waist circumference cut-points of 84.0 (74.0, 90.0) cm in South Asian women and 81.2 (71.4, 87.4) cm in African-Caribbean women were equivalent to a value of 88 cm in European women.
  
  
  CONCLUSIONS
  In prospective analyses, British South Asians and African-Caribbeans had equivalent diabetes incidence rates at substantially lower obesity levels than the conventional European cut-points.
authors.affiliation: UCL Institute of Cardiovascular Science, University College London, London.
authors.forename: T
authors.initials: T
authors.lastname: Tillin
authors.forename: N
authors.initials: N
authors.lastname: Sattar
authors.forename: I F
authors.initials: IF
authors.lastname: Godsland
authors.forename: A D
authors.initials: AD
authors.lastname: Hughes
authors.forename: N
authors.initials: N
authors.lastname: Chaturvedi
authors.forename: N G
authors.initials: NG
authors.lastname: Forouhi
mesh_terms: D000328:Adult; D000368:Aged; D044466:Asian People; D044383:Black People; D015992:Body Mass Index; D017691:Caribbean Region / Q000208:ethnology; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis / Q000453:epidemiology / Q000208:ethnology / Q000209:etiology*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D015994:Incidence; D007333:Insulin Resistance / Q000208:ethnology; D008131:London / Q000453:epidemiology; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000175:diagnosis / Q000208:ethnology / Q000503:physiopathology*; D050177:Overweight / Q000175:diagnosis / Q000208:ethnology / Q000503:physiopathology*; D011446:Prospective Studies; D012307:Risk Factors; D014504:Urban Health / Q000208:ethnology; D044465:White People