title: Effects of vitamin D2 or D3 supplementation on glycaemic control and cardiometabolic risk among people at risk of type 2 diabetes: results of a randomized double-blind placebo-controlled trial.
abstract: OBJECTIVE
  To investigate the effect of short-term vitamin D supplementation on cardiometabolic outcomes among individuals with an elevated risk of diabetes.
  
  
  METHODS
  In a double-blind placebo-controlled randomized trial, 340 adults who had an elevated risk of type 2 diabetes (non-diabetic hyperglycaemia or positive diabetes risk score) were randomized to either placebo, 100,000 IU vitamin D2 (ergocalciferol) or 100,000 IU vitamin D3 (cholecalciferol), orally administered monthly for 4 months. The primary outcome was change in glycated haemoglobin (HbA1c) between baseline and 4 months, adjusted for baseline. Secondary outcomes included: blood pressure; lipid levels; apolipoprotein levels; C-reactive protein levels; pulse wave velocity (PWV); anthropometric measures; and safety of the supplementation.
  
  
  RESULTS
  The mean [standard deviation (s.d.)] 25-hydroxyvitamin D [25(OH)D]2 concentration increased from 5.2 (4.1) to 53.9 (18.5) nmol/l in the D2 group, and the mean (s.d.) 25(OH)D3 concentration increased from 45.8 (22.6) to 83.8 (22.7) nmol/l in the D3 group. There was no effect of vitamin D supplementation on HbA1c: D2 versus placebo: -0.05% [95% confidence interval (CI) -0.11, 0.02] or -0.51 mmol/mol (95% CI -1.16, 0.14; p = 0.13); D3 versus placebo: 0.02% (95% CI -0.04, 0.08) or 0.19 mmol/mol (95% CI -0.46, 0.83; p = 0.57). There were no clinically meaningful effects on secondary outcomes, except PWV [D2 versus placebo: -0.68 m/s (95% CI -1.31, -0.05); D3 versus placebo -0.73 m/s (95% CI -1.42, -0.03)]. No important safety issues were identified.
  
  
  CONCLUSIONS
  Short-term supplementation with vitamin D2 or D3 had no effect on HbA1c. The modest reduction in PWV with both D2 and D3 relative to placebo suggests that vitamin D supplementation has a beneficial effect on arterial stiffness.
authors.affiliation: Medical Research Council Epidemiology Unit, University of Cambridge School of Clinical Medicine, Cambridge, UK.
authors.forename: N G
authors.initials: NG
authors.lastname: Forouhi
authors.affiliation: Blizard Institute, Queen Mary University of London, London, UK.
authors.forename: R K
authors.initials: RK
authors.lastname: Menon
authors.affiliation: Medical Research Council Epidemiology Unit, University of Cambridge School of Clinical Medicine, Cambridge, UK.
authors.forename: S J
authors.initials: SJ
authors.lastname: Sharp
authors.affiliation: Blizard Institute, Queen Mary University of London, London, UK.
authors.forename: N
authors.initials: N
authors.lastname: Mannan
authors.affiliation: Homerton University Hospital NHS Foundation Trust, London, UK.
authors.forename: P M
authors.initials: PM
authors.lastname: Timms
authors.affiliation: Blizard Institute, Queen Mary University of London, London, UK.
authors.forename: A R
authors.initials: AR
authors.lastname: Martineau
authors.affiliation: Medical Research Council Epidemiology Unit, University of Cambridge School of Clinical Medicine, Cambridge, UK.
authors.forename: A P
authors.initials: AP
authors.lastname: Rickard
authors.affiliation: Blizard Institute, Queen Mary University of London, London, UK.
authors.forename: B J
authors.initials: BJ
authors.lastname: Boucher
authors.affiliation: Blizard Institute, Queen Mary University of London, London, UK.|Barts Healthcare NHS Trust, London, UK.
authors.forename: T A
authors.initials: TA
authors.lastname: Chowdhury
authors.affiliation: Blizard Institute, Queen Mary University of London, London, UK.
authors.forename: C J
authors.initials: CJ
authors.lastname: Griffiths
authors.affiliation: Blizard Institute, Queen Mary University of London, London, UK.
authors.forename: S E
authors.initials: SE
authors.lastname: Greenwald
authors.affiliation: Medical Research Council Epidemiology Unit, University of Cambridge School of Clinical Medicine, Cambridge, UK.
authors.forename: S J
authors.initials: SJ
authors.lastname: Griffin
authors.affiliation: Blizard Institute, Queen Mary University of London, London, UK.
authors.forename: G A
authors.initials: GA
authors.lastname: Hitman
mesh_terms: D015652:25-Hydroxyvitamin D 2 / Q000097:blood; D000328:Adult; D000368:Aged; D002112:Calcifediol / Q000097:blood; D002318:Cardiovascular Diseases / Q000097:blood / Q000453:epidemiology / Q000517:prevention & control*; D002762:Cholecalciferol / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000453:epidemiology / Q000517:prevention & control*; D019587:Dietary Supplements / Q000009:adverse effects; D004311:Double-Blind Method; D004739:England / Q000453:epidemiology; D004872:Ergocalciferols / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D005240:Feasibility Studies; D005260:Female; D005500:Follow-Up Studies; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D063177:Pulse Wave Analysis; D012306:Risk; D059289:Vascular Stiffness
chemical_list: D015652:25-Hydroxyvitamin D 2; D002112:Calcifediol; D002762:Cholecalciferol; D004872:Ergocalciferols; D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human
keywords: intervention; placebo; pulse wave velocity; randomized; trial; type 2 diabetes; vitamin D2; vitamin D3