Efficacy of vitamin D supplementation on glycemic control in type 2 diabetes patients: A meta-analysis of interventional studies

Medicine (Baltimore). 2019 Apr;98(14):e14970. doi: 10.1097/MD.0000000000014970.


Background: Conflicting evidence exists on the effect of vitamin D supplementation on glucose metabolism in subjects with type 2 diabetes (T2D). Therefore, this meta-analysis focuses on the relationship between vitamin D intervention and glycaemic control in subjects with T2D.

Methods: We reviewed available randomized controlled trials (RCTs) studies from the establishment time of each database to March 31, 2018. Stata 13.0 software was used to evaluate the included literature.

Results: Finally, a total of 19 RCT studies involving 747 intervention subjects and 627 placebo controls were included in this meta-analysis. Meta-analysis results showed that compared with the control group, the short-term vitamin D supplementation group had a decline in hemoglobin A1c (HbA1c), insulin resistance, and insulin. The Standard Mean Difference (SMD) (95% CI [95% confidence interval]) of HbA1c, insulin resistance, and insulin were -0.17 (-0.29, -0.05), -0.75 (-0.97, -0.53), -0.57 (-0.78, -0.35), respectively with all P value <.05. But there were no significant differences in long-term follow-up vitamin D intervention.

Conclusion: Vitamin D supplementation in T2D patients can improve HbA1c, insulin resistance, and insulin in short-term intervention, suggesting that vitamin D can be considered as a therapeutic agent along with the other treatments for T2D.

Publication types

  • Comparative Study
  • Meta-Analysis
  • Systematic Review

MeSH terms

  • Blood Glucose / drug effects*
  • Diabetes Mellitus, Type 2 / drug therapy*
  • Diabetes Mellitus, Type 2 / epidemiology
  • Female
  • Glycated Hemoglobin / drug effects
  • Humans
  • Insulin / metabolism
  • Insulin Resistance / physiology
  • Randomized Controlled Trials as Topic
  • Vitamin D / administration & dosage
  • Vitamin D / therapeutic use*
  • Vitamins / therapeutic use


  • Blood Glucose
  • Glycated Hemoglobin A
  • Insulin
  • Vitamins
  • Vitamin D