title: Association of vitamin D with insulin resistance and beta-cell dysfunction in subjects at risk for type 2 diabetes.
abstract: OBJECTIVE
  To examine cross-sectional associations of serum vitamin D [25-hydroxyvitamin D, 25(OH)D] concentration with insulin resistance (IR) and beta-cell dysfunction in 712 subjects at risk for type 2 diabetes.
  
  
  METHODS
  Serum 25(OH)D was determined using a chemiluminescence immunoassay. Insulin sensitivity/resistance were measured using the Matsuda insulin sensitivity index for oral glucose tolerance tests (IS(OGTT)) and homeostasis model assessment of insulin resistance HOMA-IR. beta-Cell function was determined using both the insulinogenic index (IGI) divided by HOMA-IR (IGI/IR) and the insulin secretion sensitivity index-2 (ISSI-2). RESULTS Linear regression analyses indicated independent associations of 25(OH)D with IS(OGTT) and HOMA-IR (beta = 0.004, P = 0.0003, and beta = -0.003, P = 0.0072, respectively) and with IGI/IR and ISSI-2 (beta = 0.004, P = 0.0286, and beta = 0.003, P = 0.0011, respectively) after adjusting for sociodemographics, physical activity, supplement use, parathyroid hormone, and BMI.
  
  
  CONCLUSIONS
  Vitamin D may play a role in the pathogenesis of type 2 diabetes, as 25(OH)D concentration was independently associated with both insulin sensitivity and beta-cell function among individuals at risk of type 2 diabetes.
authors.affiliation: Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Sheena
authors.initials: S
authors.lastname: Kayaniyil
authors.forename: Reinhold
authors.initials: R
authors.lastname: Vieth
authors.forename: Ravi
authors.initials: R
authors.lastname: Retnakaran
authors.forename: Julia A
authors.initials: JA
authors.lastname: Knight
authors.forename: Ying
authors.initials: Y
authors.lastname: Qi
authors.forename: Hertzel C
authors.initials: HC
authors.lastname: Gerstein
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Perkins
authors.forename: Stewart B
authors.initials: SB
authors.lastname: Harris
authors.forename: Bernard
authors.initials: B
authors.lastname: Zinman
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Hanley
mesh_terms: D000328:Adult; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D050417:Insulin-Secreting Cells / Q000473:pathology*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D