The Effect of Vitamin D Supplementation on Glycemic Control and Cardiovascular Risk Factors in Type 2 Diabetes: An Updated Systematic Review and Meta-Analysis of Clinical Trials

J Diabetes Res. 2024 Sep 10:2024:9960656. doi: 10.1155/2024/9960656. eCollection 2024.

Abstract

Background and Aims: The purpose of this meta-analysis was to investigate the effect of vitamin D supplementation on hemoglobin A1C (HbA1C), fasting blood sugar (FBS), low-density lipoprotein (LDL), high-density lipoprotein (HDL), systolic blood pressure (SBP), and the total vitamin D level in patients with Type 2 diabetes (T2DM). Methods: A systematic search was conducted in databases such as PubMed (Medline), Scopus, Embase, Web of Science, Cochrane Library, and ClinicalTrials.gov using relevant keywords from January 1990 to January 2024. After screening and extracting data, a qualitative evaluation of articles was performed using the Cochrane risk-of-bias tool for randomized trials (RoB 2). Results: The findings revealed that vitamin D supplementation significantly decreased the mean HbA1C (SMD: -0.15; 95% CI: -0.29, -0.20; I square: 79.76%; p value < 0.001) and mean FBS (SMD: -0.28; 95% CI: -0.40, -0.15; I square: 70.13%; p value < 0.001), lowered SBP (SMD: -0.06; 95% CI: -0.16, -0.05; I square: 39.63%; p value = 0.23), and reduced LDL (SMD: -0.11; 95% CI: -0.28, -0.05; I square: 73.66%; p value < 0.001). Furthermore, vitamin D supplementation increased the average HDL (SMD: 0.13; 95% CI: 0.04, 0.29; I square: 79.33%; p value < 0.001) and vitamin D levels (SMD: 1.78; 95% CI: 1.53, 2.04; I square: 91.92%; p value < 0.001) in patients with T2DM. Subgroup analyses showed that weight gain, BMI, and duration of the disease could reduce the effect of vitamin D supplementation on diabetes control in affected patients. Conclusion: The results also indicated that taking vitamin D supplements in the amount of 50,000 IU had a significant effect on reducing the indicators related to diabetes control. Based on the combined evidence, the findings of this meta-analysis suggest that vitamin D supplementation can significantly improve glycemic control and reduce the risk of complications associated with T2DM, especially cardiovascular diseases (CVDs).

Keywords: Type 2 diabetes; meta-analysis; systematic review; vitamin D supplementation.

Publication types

  • Meta-Analysis
  • Systematic Review

MeSH terms

  • Blood Glucose / drug effects
  • Blood Glucose / metabolism
  • Blood Pressure / drug effects
  • Cardiovascular Diseases* / epidemiology
  • Cardiovascular Diseases* / etiology
  • Cardiovascular Diseases* / prevention & control
  • Diabetes Mellitus, Type 2* / blood
  • Diabetes Mellitus, Type 2* / complications
  • Diabetes Mellitus, Type 2* / diet therapy
  • Dietary Supplements*
  • Glycated Hemoglobin / analysis
  • Glycated Hemoglobin / metabolism
  • Glycemic Control* / methods
  • Heart Disease Risk Factors*
  • Humans
  • Randomized Controlled Trials as Topic
  • Vitamin D* / administration & dosage
  • Vitamin D* / blood

Substances

  • Blood Glucose
  • Glycated Hemoglobin
  • hemoglobin A1c protein, human
  • Vitamin D