title: Effect of vitamin D3 supplementation on glycated hemoglobin (HbA1c), fructosamine, serum lipids, and body mass index: a randomized, double-blinded, placebo-controlled trial among healthy immigrants living in Norway.
abstract: OBJECTIVE
  Despite the suggested role of vitamin D in the prevention of diabetes and cardiovascular disease or its risk factors, the evidence is not consistent and there is a paucity of randomized controlled trials in this field. We aimed to investigate the effect of 16-week daily vitamin D3 supplementation on glycated hemoglobin (HbA1c), fructosamine, body mass index (BMI), and serum lipids.
  
  
  METHODS
  Double-blind, randomized, placebo-controlled trial.
  
  
  METHODS
  Immigrant community centers in Oslo, Norway.
  
  
  METHODS
  251 healthy adults aged 18-50 years with a non-Western immigrant background. All participants performed the baseline test and 215 (86%) returned to the follow-up test.
  
  
  METHODS
  16 weeks of daily oral supplementation with either 10 μg vitamin D3, 25 μg vitamin D3, or placebo.
  
  
  METHODS
  Difference in absolute change during the 16-week intervention between the intervention groups combined (10 or 25 μg of vitamin D3/day) and placebo, in HbA1c, fructosamine, serum lipids (total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides), and BMI.
  
  
  RESULTS
  A total of 215 (86%) participants completed the study. Serum 25-hydroxyvitamin D increased from 29 nmol/L at baseline to 49 nmol/L after intervention, with little change in the placebo group. However, there was no difference in change of HbA1c between those receiving vitamin D3 compared with placebo (mean difference: 0.01% (95% CI -0.04 to 0.06, p=0.7)). Neither did the vitamin D3 supplementation have any effect on the other end points: fructosamine, serum lipids, and BMI.
  
  
  CONCLUSIONS
  16-week vitamin D3 supplementation to healthy immigrants from South Asia, the Middle East, or Africa and now living in Norway with low vitamin D status did not improve HbA1c, fructosamine, lipid profiles, or BMI. An updated meta-analysis of similar published trials showed that our results were generally consistent with those of other studies.
  
  
  BACKGROUND
  NCT01263288.
authors.affiliation: Department of Community Medicine , Institute of Health and Society, University of Oslo , Oslo , Norway.
authors.forename: Ahmed A
authors.initials: AA
authors.lastname: Madar
authors.affiliation: Department of General Practice , Institute of Health and Society, University of Oslo , Oslo , Norway.
authors.forename: Kirsten V
authors.initials: KV
authors.lastname: Knutsen
authors.affiliation: Division of Epidemiology , Norwegian Institute of Public Health , Oslo , Norway.
authors.forename: Lars C
authors.initials: LC
authors.lastname: Stene
authors.affiliation: Department of General Practice , Institute of Health and Society, University of Oslo , Oslo , Norway.
authors.forename: Mette
authors.initials: M
authors.lastname: Brekke
authors.affiliation: Department of Community Medicine , Institute of Health and Society, University of Oslo , Oslo , Norway ; Division of Epidemiology , Norwegian Institute of Public Health , Oslo , Norway.
authors.forename: Haakon E
authors.initials: HE
authors.lastname: Meyer
authors.affiliation: Department of General Practice , Institute of Health and Society, University of Oslo , Oslo , Norway.
authors.forename: Per
authors.initials: P
authors.lastname: Lagerløv
keywords: Body Mass Index; Glycated Hemoglobin; Serum Lipids; Vitamin D