title: Associations of circulating 25(OH)D with cardiometabolic disorders underlying type 2 diabetes mellitus in an Aboriginal Canadian community.
abstract: OBJECTIVE
  To investigate the associations of 25-hydroxyvitamin D (25(OH)D) with insulin resistance (IR), beta-cell function and metabolic syndrome (MetS) in a First Nations population.
  
  
  METHODS
  We conducted a cross-sectional analysis using data from the Sandy Lake Health and Diabetes Project (2003-2005). A total of 390 participants (>12 y) were assessed for 25(OH)D, fasting glucose, insulin, lipids, blood pressure, inflammatory markers, anthropometric and lifestyle variables and a 75-g oral glucose tolerance test was administered. IR was calculated using the Matsuda insulin sensitivity index (ISOGTT) and the computational homeostasis model assessment of IR (HOMA2-IR). Beta-cell function was calculated using the insulinogenic index (IGI) divided by HOMA-IR (IGI/IR) and the insulin secretion sensitivity index-2 (ISSI-2). The 2009 harmonized criteria were used to define MetS.
  
  
  RESULTS
  Higher 25(OH)D was associated with a decreased prevalence of dysglycemia (OR = 0.71 95% CI, 0.51-0.97 per SD increase). In addition, there were significant associations of 25(OH)D with measures of insulin action (ISOGTT; beta=0.31; 95% CI, 0.12, 0.49; HOMA2-IR; beta = -29; 95% CI -0.46, -0.11 and beta-cell function (ISSI-2; beta = 0.15; 95% CI, 0.02, 0.28). The prevalence of MetS was 41%. There was a decreased risk (OR=0.73, 95% CI 0.56, 0.94) of MetS per SD increase in baseline 25(OH)D. Finally, there was a significant positive association of 25(OH)D with adiponectin (beta = 0.16; 95% CI = 0.01, 0.31).
  
  
  CONCLUSIONS
  These results support a potential role for vitamin D metabolism in the natural history of T2DM among Aboriginal Canadians, although carefully designed randomized trials will be required to establish causality.
authors.affiliation: Department of Nutritional Sciences, University of Toronto, Toronto, ON, Canada.
authors.forename: Sudaba
authors.initials: S
authors.lastname: Mansuri
authors.affiliation: Office of Biotechnology, Genomics and Population Health, Public Health Agency of Canada, Toronto, ON, Canada.
authors.forename: Alaa
authors.initials: A
authors.lastname: Badawi
authors.affiliation: Department of Nutritional Sciences, University of Toronto, Toronto, ON, Canada.
authors.forename: Sheena
authors.initials: S
authors.lastname: Kayaniyil
authors.affiliation: Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, ON, Canada.
authors.forename: David E
authors.initials: DE
authors.lastname: Cole
authors.affiliation: Center for Studies in Family Medicine, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.
authors.forename: Stewart B
authors.initials: SB
authors.lastname: Harris
authors.affiliation: Sandy Lake Health and Diabetes Project, Sandy Lake, ON, Canada.
authors.forename: Mary
authors.initials: M
authors.lastname: Mamakeesick
authors.affiliation: Keenan Research Centre of the Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, ON, Canada.
authors.forename: Jonathon
authors.initials: J
authors.lastname: Maguire
authors.affiliation: Division of Endocrinology, University of Toronto, Toronto, ON, Canada; Leadership Sinai Centre for Diabetes, Mount Sinai Hospital, Toronto, ON, Canada; Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, ON, Canada.
authors.forename: Bernard
authors.initials: B
authors.lastname: Zinman
authors.affiliation: Keenan Research Centre of the Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, ON, Canada.
authors.forename: Philip W
authors.initials: PW
authors.lastname: Connelly
authors.affiliation: Department of Nutritional Sciences, University of Toronto, Toronto, ON, Canada; Division of Endocrinology, University of Toronto, Toronto, ON, Canada; Leadership Sinai Centre for Diabetes, Mount Sinai Hospital, Toronto, ON, Canada. Electronic address: anthony.hanley@utoronto.ca.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Hanley
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D002170:Canada / Q000453:epidemiology; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000150:complications / Q000208:ethnology; D005260:Female; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology; D008297:Male; D024821:Metabolic Syndrome / Q000097:blood / Q000150:complications* / Q000208:ethnology; D015995:Prevalence; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D015415:Biomarkers; D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: 25(OH)D; Aboriginal; Beta cell dysfunction; Insulin resistance; Metabolic syndrome