title: Plasma isoflavone concentration is associated with decreased risk of type 2 diabetes in Korean women but not men: results from the Korean Genome and Epidemiology Study.
abstract: OBJECTIVE
  To examine the association between soybean products and risk of type 2 diabetes, we measured four isoflavone biological markers--genistein, daidzein, glycitein and equol--in a nested case-control study.
  
  
  METHODS
  The study population was composed of 693 cases (316 women and 377 men) and 698 matched controls (317 women and 381 men) within the Korean Genome and Epidemiology Study. The concentrations of isoflavone biomarkers were measured using HPLC-MS/MS on plasma samples that were collected at baseline. A stratified analysis was undertaken to examine the association between plasma isoflavone concentrations and risk of type 2 diabetes according to sex and equol production. Logistic regression models were used to compute ORs and 95% CIs adjusted for confounders.
  
  
  RESULTS
  In women, compared with the lowest quartile of plasma concentration of genistein, the highest quartile exhibited a significantly decreased risk of diabetes (OR 0.58, 95% CI 0.35, 0.95). When stratified by equol-producing status in women, the OR for diabetes in the highest vs the lowest quartile of genistein concentration was 0.31 (95% CI 0.16, 0.60) in equol producers, but genistein concentration was not associated with risk of diabetes in equol non-producers (p for interaction = 0.013). In men, isoflavone concentrations were not associated with risk of diabetes, regardless of equol-producing status.
  
  
  CONCLUSIONS
  High plasma concentrations of genistein were associated with a decreased risk of type 2 diabetes in women. This inverse association was prominent in equol-producing participants. These results suggest a beneficial effect of a high intake of soybean products on risk of type 2 diabetes in women.
authors.affiliation: Department of Preventive Medicine, Gachon University, Incheon, Korea.
authors.forename: Kwang-Pil
authors.initials: KP
authors.lastname: Ko
authors.forename: Cheong-Sik
authors.initials: CS
authors.lastname: Kim
authors.forename: Younjhin
authors.initials: Y
authors.lastname: Ahn
authors.forename: Seon-Joo
authors.initials: SJ
authors.lastname: Park
authors.forename: Yeon-Jeong
authors.initials: YJ
authors.lastname: Kim
authors.forename: Jae Kyung
authors.initials: JK
authors.lastname: Park
authors.forename: Young-Khi
authors.initials: YK
authors.lastname: Lim
authors.forename: Keun-Young
authors.initials: KY
authors.lastname: Yoo
authors.forename: Sung Soo
authors.initials: SS
authors.lastname: Kim
mesh_terms: D044466:Asian People / Q000235:genetics; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D002851:Chromatography, High Pressure Liquid; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis / Q000208:ethnology / Q000235:genetics / Q000517:prevention & control*; D004032:Diet; D060754:Equol / Q000097:blood; D005260:Female; D019833:Genistein / Q000097:blood; D015894:Genome, Human; D006801:Humans; D007529:Isoflavones / Q000097:blood*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011446:Prospective Studies; D065840:Protective Factors; D056910:Republic of Korea / Q000453:epidemiology; D018570:Risk Assessment; D012307:Risk Factors; D012737:Sex Factors; D045730:Soy Foods; D053719:Tandem Mass Spectrometry
chemical_list: D007529:Isoflavones; D060754:Equol; C004742:daidzein; C086566:glycitein; D019833:Genistein