title: [Efficacy and safety of vitamin D for type 2 diabetes mellitus: a systematic review].
abstract: OBJECTIVE
  To evaluate the efficacy and safety of vitamin D (VD) for patients with type 2 diabetes mellitus.
  
  
  METHODS
  Randomized controlled trials (RCT) were identified from CBM (1978.1-2012.9), CNKI (1979.1-2012.9), Pubmed (1950.1-2012.9), EMbase (1970.1-2012.9) and Cochrane library (issue 4, 2012). Publications of the RCT on the treatment of type 2 diabetes mellitus with VD were included and analyzed according to the criteria of Cochrane handbook.
  
  
  RESULTS
  Six RCT involving 328 patients were included. Meta-analysis indicated that VD caused a reduction in glycosylated hemoglobin A 1c (HbA 1c) (P = 0.05) but not in fasting plasma glucose (FPG), homeostasis model assessment index of insulin resistance (HOMA-IR) and failed to improve quantitative insulin sensitivity check index (QUICKI) and homeostasis model assessment index of β cell function (HOMA-β) (P > 0.05). As reported in a trial, the side effect of VD was hypercalcemia.
  
  
  CONCLUSIONS
  VD may have positive effects on patients with type 2 diabetes mellitus. However, the evidence is weak due to the general low methodological quality. Thus we have not made a reliable conclusion about the effects of VD for type 2 diabetes mellitus at the moment. Further larger, randomized, double-blind, placebo-controlled and multicenter trials are warranted.
authors.affiliation: Department of Endocrinology & Metabolism, Sichuan University, Chengdu, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Gao
authors.forename: Da-wei
authors.initials: DW
authors.lastname: Chen
authors.forename: Guan-jian
authors.initials: GJ
authors.lastname: Liu
authors.forename: Xing-wu
authors.initials: XW
authors.lastname: Ran
mesh_terms: D001786:Blood Glucose; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy*; D006801:Humans; D007333:Insulin Resistance; D016032:Randomized Controlled Trials as Topic; D016896:Treatment Outcome; D014807:Vitamin D / Q000627:therapeutic use*
chemical_list: D001786:Blood Glucose; D014807:Vitamin D