title: Effects of vitamin D on blood pressure in patients with type 2 diabetes mellitus.
abstract: OBJECTIVE
  Previous studies have suggested that vitamin D supplementation may decrease blood pressure in patients with type 2 diabetes, although conflicting results have been reported. The purpose of this meta-analysis was to evaluate the effects of the vitamin D supplementation on blood pressure in patients with type 2 diabetes.
  
  
  METHODS
  A meta-analysis of published randomized controlled trials was conducted. Eligible studies were identified via a literature search of the MEDLINE (PubMed), EMBASE, and Cochrane Library databases through to May 25, 2015. The endpoint of the analysis was the change in blood pressure due to vitamin D treatment in patients with type 2 diabetes. These changes were calculated as the difference between the baseline and final measurements performed in each study. A fixed-effects model was used to calculate the combined effect estimates; in the presence of heterogeneity, a random-effects model was used.
  
  
  RESULTS
  A total of 15 articles were included in the meta-analysis. All 15 articles, including 1,134 patients with type 2 diabetes, were analyzed for systolic blood pressure (SBP), and 13 articles, including 793 patients, were analyzed for diastolic blood pressure (DBP). The combined-effect estimate of vitamin D intervention on SBP was -0.121 mmHg (95% confidence interval (CI) -0.355 to 0.113, p = 0.311), and considerable heterogeneity was observed between studies (p < 0.001, I(2)= 74.2%). For DBP, the combined effect estimate was -0.160 mmHg (95% CI -0.298 to -0.022, p = 0.023), and no heterigenieity was observed (p = 0.673, I(2) = 0.0%).
  
  
  CONCLUSIONS
  This study is the first meta-analysis of the effect of vitamin D supplementation on blood pressure in patients with type 2 diabetes. This meta-analysis demonstrated that vitamin D supplementation may result in a reduction in DBP in patients with type 2 diabetes. However, additional studies with large sample sizes and longer durations are needed to establish a relationship between vitamin D and blood pressure in patients with type 2 diabetes.
authors.forename: Kyeong Ju
authors.initials: KJ
authors.lastname: Lee
authors.forename: Yu Jeung
authors.initials: YJ
authors.lastname: Lee
mesh_terms: D001794:Blood Pressure / Q000187:drug effects*; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D019587:Dietary Supplements; D006801:Humans; D014807:Vitamin D / Q000494:pharmacology*
chemical_list: D014807:Vitamin D