title: The effects of vitamin D₂ or D₃ supplementation on glycaemic control and related metabolic parameters in people at risk of type 2 diabetes: protocol of a randomised double-blind placebo-controlled trial.
abstract: BACKGROUND
  The global prevalence of type 2 diabetes is increasing. Effective strategies to address this public health challenge are currently lacking. A number of epidemiological studies have reported associations between low concentrations of 25-hydroxy vitamin D and the incidence of diabetes, but a causal link has not been established. We investigate the effect of vitamin D supplementation on the metabolic status of individuals at increased risk of developing type 2 diabetes.
  
  
  METHODS
  In a randomised double-blind placebo-controlled trial individuals identified as having a high risk of type 2 diabetes (non-diabetic hyperglycaemia or positive diabetes risk score) are randomised into one of three groups and given 4 doses of either placebo, or 100,000 IU Vitamin D₂ (ergocalciferol) or 100,000 IU Vitamin D₃ (cholecalciferol) at monthly intervals. The primary outcome measure is the change in glycated haemoglobin level between baseline and 4 months. Secondary outcome measures include blood pressure, lipid levels, apolipoproteins, highly sensitive C-reactive protein, parathyroid hormone (PTH) and safety of supplementation. and C-reactive protein. The trial is being conducted at two sites (London and Cambridge, U.K.) and a total of 342 participants are being recruited.
  
  
  CONCLUSIONS
  Trial data examining whether supplementation of vitamin D improves glycaemic status and other metabolic parameters in people at risk of developing type 2 diabetes are sparse. This trial will evaluate the causal role of vitamin D in hyperglycaemia and risk of type 2 diabetes. Specific features of this trial include recruitment of participants from different ethnic groups, investigation of the relative effectiveness and safety of vitamin D₂ and D₃ and an evidence based approach to determination of the dose of supplementation.
  
  
  BACKGROUND
  EudraCT2009-011264-11; ISRCTN86515510.
authors.forename: Ravi K
authors.initials: RK
authors.lastname: Menon
authors.forename: Anna P
authors.initials: AP
authors.lastname: Rickard
authors.forename: Nasima
authors.initials: N
authors.lastname: Mannan
authors.forename: Peter M
authors.initials: PM
authors.lastname: Timms
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Sharp
authors.forename: Adrian
authors.initials: A
authors.lastname: Martineau
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Boucher
authors.forename: Tahseen A
authors.initials: TA
authors.lastname: Chowdhury
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Griffiths
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Griffin
authors.affiliation: Blizard Institute, Queen Mary University of London, London, UK. g.a.hitman@qmul.ac.uk.
authors.forename: Graham A
authors.initials: GA
authors.lastname: Hitman
authors.forename: Nita G
authors.initials: NG
authors.lastname: Forouhi
mesh_terms: D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000187:drug effects; D002097:C-Reactive Protein / Q000187:drug effects; D002762:Cholecalciferol / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000517:prevention & control*; D019587:Dietary Supplements / Q000706:statistics & numerical data*; D004311:Double-Blind Method; D004872:Ergocalciferols / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use*; D005260:Female; D005500:Follow-Up Studies; D006442:Glycated Hemoglobin / Q000187:drug effects; D006801:Humans; D006943:Hyperglycemia / Q000097:blood / Q000188:drug therapy*; D008131:London; D008297:Male; D008875:Middle Aged; D012306:Risk; D016896:Treatment Outcome; D014815:Vitamins / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use
chemical_list: D001786:Blood Glucose; D002097:C-Reactive Protein; D002762:Cholecalciferol; D004872:Ergocalciferols; D006442:Glycated Hemoglobin; D014815:Vitamins