title: Serum 25-hydroxyvitamin D and markers of insulin resistance in a Japanese working population.
abstract: OBJECTIVE
  The association between vitamin D status and insulin resistance (IR) has been less studied among Asians, and it remains elusive whether calcium could modify such an association. We examined the association of serum 25-hydroxyvitamin D (25(OH)D) concentrations with IR markers and the potential effect modification by calcium intake among a Japanese population.
  
  
  METHODS
  The authors analyzed data (n=494) from a cross-sectional survey conducted in 2009 among a Japanese working population aged 20-68 years. Fasting serum 25(OH)D and insulin, as well as fasting plasma glucose were determined, and homeostatic model assessment of IR (HOMA-IR) was calculated. Calcium intake was assessed using a validated diet history questionnaire. Multiple linear regression was done with adjustment of potential confounding variables.
  
  
  RESULTS
  Fasting insulin and HOMA-IR were significantly inversely associated with 25(OH)D concentration across quartiles of 25(OH)D after fully adjusting for covariates (P(trend)=0.04 and 0.02, respectively). Across clinically relevant categories of 25(OH)D, compared with participants in the vitamin D sufficiency group, those in the vitamin D insufficiency group had a 5% higher HOMA-IR score, and those in the hypovitaminosis D group had an 18% higher HOMA-IR score (P(trend)=0.01). In an analysis by calcium intake, the HOMA-IR score was highest among participants with both a low calcium intake and lowest 25(OH)D concentrations, with significant inverse trend being observed in the group with lower calcium intake (P(trend)=0.02).
  
  
  CONCLUSIONS
  Our findings suggest that low vitamin D status is associated with IR among Japanese adults.
authors.affiliation: Department of Epidemiology and Prevention, Clinical Research Center, National Center for Global Health and Medicine, Tokyo, Japan. pham@ri.ncgm.go.jp
authors.forename: N M
authors.initials: NM
authors.lastname: Pham
authors.forename: S
authors.initials: S
authors.lastname: Akter
authors.forename: K
authors.initials: K
authors.lastname: Kurotani
authors.forename: A
authors.initials: A
authors.lastname: Nanri
authors.forename: M
authors.initials: M
authors.lastname: Sato
authors.forename: H
authors.initials: H
authors.lastname: Hayabuchi
authors.forename: K
authors.initials: K
authors.lastname: Yasuda
authors.forename: T
authors.initials: T
authors.lastname: Mizoue
mesh_terms: D000328:Adult; D000368:Aged; D044466:Asian People; D015415:Biomarkers / Q000097:blood; D002136:Calcium, Dietary / Q000008:administration & dosage*; D003430:Cross-Sectional Studies; D004034:Diet Surveys; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood*; D007333:Insulin Resistance; D007564:Japan; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011795:Surveys and Questionnaires; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D002136:Calcium, Dietary; D007328:Insulin; D014807:Vitamin D; C104450:25-hydroxyvitamin D