title: Effect of vitamin D supplementation on oral glucose tolerance in individuals with low vitamin D status and increased risk for developing type 2 diabetes (EVIDENCE): A double-blind, randomized, placebo-controlled clinical trial.
abstract: Low serum 25-hydroxyvitamin-D (25(OH)D) concentrations are associated with insulin resistance, β-cell dysfunction and type 2 diabetes. We conducted a 24-week double-blind, randomized, placebo-controlled trial to examine the effect of 28 000 IU of vitamin D3once weekly on plasma glucose after a 2 hour-75 g oral glucose tolerance test (2hrPC glucose), insulin sensitivity and β-cell function.
  
  
  
  A total of 71 participants with serum 25(OH)D ≤65 nmol/L, impaired fasting glucose and elevated glycated hemoglobin were randomly assigned to receive 28 000 IU of vitamin D3(VitD; n = 35) or placebo (n = 36) in cheese once weekly for 24 weeks. The primary outcome was the change in 2hPC glucose. Secondary outcomes were fasting glucose, fasting and postprandial insulin, indices of insulin sensitivity and β-cell function, glycated hemoglobin and lipid profile. Participants underwent an oral glucose tolerance test to determine 2hPC glucose.
  
  
  
  Mean baseline serum 25(OH)D was 48.1 and 47.6 nmol/L in the VitD and placebo groups, respectively. Serum 25(OH)D significantly increased to 98.7 nmol/L (51 nmol/L increase; P < .0001) in the VitD group. No significant differences in fasting ( P = .42) or 2hPC glucose ( P = .55) or other indices of glucose metabolism, including β-cell function and insulin sensitivity, were observed between groups. A subgroup analysis of individuals with 25(OH)D < 50 nmol/L and prediabetes did not change these results. The VitD group exhibited a significant reduction in LDL cholesterol (-0.27 vs 0.01 mmol/L, P = .03).
  
  
  
  Weekly doses of vitamin D3in individuals with suboptimal vitamin D levels who were at risk for type 2 diabetes did not improve oral glucose tolerance or markers of glycaemic status.
authors.affiliation: Department of Nutritional Sciences, University of Toronto, Toronto, Canada.
authors.forename: Tracy S
authors.identifier: 0000-0001-6980-4347
authors.initials: TS
authors.lastname: Moreira-Lucas
authors.affiliation: Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Canada.
authors.forename: Alison M
authors.initials: AM
authors.lastname: Duncan
authors.affiliation: Institut de Recherches Cliniques de Montréal & Nutrition Department, Université de Montréal, Montreal, Canada.
authors.forename: Rémi
authors.initials: R
authors.lastname: Rabasa-Lhoret
authors.affiliation: Department of Nutritional Sciences, University of Toronto, Toronto, Canada.
authors.forename: Reinhold
authors.initials: R
authors.lastname: Vieth
authors.affiliation: Department of Statistical Sciences, University of Toronto, Toronto, Canada.
authors.forename: Alison L
authors.initials: AL
authors.lastname: Gibbs
authors.affiliation: Public Health Risk Science Division, Public Health Agency of Canada, Toronto, Canada.
authors.forename: Alaa
authors.initials: A
authors.lastname: Badawi
authors.affiliation: Department of Nutritional Sciences, University of Toronto, Toronto, Canada.
authors.forename: Thomas M S
authors.initials: TM
authors.lastname: Wolever
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism*; D002762:Cholecalciferol / Q000627:therapeutic use*; D008078:Cholesterol, LDL / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology / Q000378:metabolism; D019587:Dietary Supplements; D004311:Double-Blind Method; D005215:Fasting; D005260:Female; D005951:Glucose Tolerance Test; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000378:metabolism; D007333:Insulin Resistance; D050417:Insulin-Secreting Cells / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D019518:Postprandial Period; D011236:Prediabetic State / Q000453:epidemiology / Q000378:metabolism*; D012306:Risk; D014807:Vitamin D / Q000031:analogs & derivatives / Q000378:metabolism; D014808:Vitamin D Deficiency / Q000188:drug therapy* / Q000453:epidemiology / Q000378:metabolism; D014815:Vitamins / Q000627:therapeutic use*
chemical_list: D001786:Blood Glucose; D002762:Cholecalciferol; D008078:Cholesterol, LDL; D006442:Glycated Hemoglobin; D007328:Insulin; D014807:Vitamin D; D014815:Vitamins; C517652:hemoglobin A1c protein, human; C104450:25-hydroxyvitamin D
keywords: beta cell; clinical trial; dietary; insulin resistance; intervention; randomized trial