title: Association of African genetic ancestry with fasting glucose and HbA1c levels in non-diabetic individuals: the Boston Area Community Health (BACH) Prediabetes Study.
abstract: OBJECTIVE
  To test among diabetes-free urban community-dwelling adults the hypothesis that the proportion of African genetic ancestry is positively associated with glycaemia, after accounting for other continental ancestry proportions, BMI and socioeconomic status (SES).
  
  
  METHODS
  The Boston Area Community Health cohort is a multi-stage 1:1:1 stratified random sample of self-identified African-American, Hispanic and white adults from three Boston inner city areas. We measured 62 ancestry informative markers, fasting glucose (FG), HbA1c, BMI and SES (income, education, occupation and insurance status) and analysed 1,387 eligible individuals (379 African-American, 411 Hispanic, 597 white) without clinical or biochemical evidence of diabetes. We used three-heritage multinomial linear regression models to test the association of FG or HbA1c with genetic ancestry proportion adjusted for: (1) age and sex; (2) age, sex and BMI; and (3) age, sex, BMI and SES.
  
  
  RESULTS
  Mean age- and sex-adjusted FG levels were 5.73 and 5.54 mmol/l among those with 100% African or European ancestry, respectively. Using per cent European ancestry as the referent, each 1% increase in African ancestry proportion was associated with an age- and sex-adjusted FG increase of 0.0019 mmol/l (p = 0.01). In the BMI- and SES-adjusted model the slope was 0.0019 (p = 0.02). Analysis of HbA1c gave similar results.
  
  
  CONCLUSIONS
  A greater proportion of African genetic ancestry is independently associated with higher FG levels in a non-diabetic community-based cohort, even accounting for other ancestry proportions, obesity and SES. The results suggest that differences between African-Americans and whites in type 2 diabetes risk may include genetically mediated differences in glucose homeostasis.
authors.affiliation: Division of General Internal Medicine, Department of Medicine, Massachusetts General Hospital, 50 Staniford St, 9th Floor, Boston, MA, 02114, USA, jmeigs@partners.org.
authors.forename: James B
authors.initials: JB
authors.lastname: Meigs
authors.forename: Richard W
authors.initials: RW
authors.lastname: Grant
authors.forename: Rebecca
authors.initials: R
authors.lastname: Piccolo
authors.forename: Lenny
authors.initials: L
authors.lastname: López
authors.forename: Jose C
authors.initials: JC
authors.lastname: Florez
authors.forename: Bianca
authors.initials: B
authors.lastname: Porneala
authors.forename: Lisa
authors.initials: L
authors.lastname: Marceau
authors.forename: John B
authors.initials: JB
authors.lastname: McKinlay
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D044383:Black People; D005215:Fasting / Q000097:blood; D005260:Female; D005947:Glucose / Q000378:metabolism*; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011236:Prediabetic State / Q000097:blood; D001741:Black or African American
chemical_list: D005947:Glucose; D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human