The effects of vitamin C supplementation on glycemic control in patients with type 2 diabetes: A systematic review and meta-analysis

Nosratabadi S 1 , Ashtary-Larky D 2 , Hosseini F 3 , Namkhah Z 4 , Mohammadi S 5 , Salamat S 6 Show all authors , Nadery M 7 , Yarmand S 8 , Zamani M 9 , Wong A 10 , Asbaghi O 11

Affiliations 

  • 1 Department of Nutrition, Electronic Health and Statistics Surveillance Research Center, Science and Research Branch, Islamic Azad University, Tehran, Iran. Electronic address: saeednosratabadi1995@gmail.com
  • 2 Nutrition and Metabolic Diseases Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran. Electronic address: Damoon_ashtary@yahoo.com
  • 3 Department of Clinical Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Science, Tehran, Iran. Electronic address: Sfatemehosseini95@gmail.com
  • 4 Department of Nutrition, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran. Electronic address: namkhah.zahra@gmail.com
  • 5 Department of Social and Preventive Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia. Electronic address: shooka.mohammadi@gmail.com
  • 6 Department of Nutrition, Faculty of Allied Medical Sciences, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran. Electronic address: shekooofeh@yahoo.com
  • 7 Department of Dietetics and Nutrition, Robert Stempel College of Public Health & Social Work, Florida International University, Miami, Florida, USA. Electronic address: mnade017@fiu.edu
  • 8 School of Nutrition and Food Sciences, Shiraz University of Medical Sciences, Shiraz, Iran. Electronic address: yarmandsazin@yahoo.com
  • 9 Department of Clinical Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences, Tehran, Iran. Electronic address: md_zamany@yahoo.com
  • 10 Department of Health and Human Performance, Marymount University, Arlington, Virginia, USA. Electronic address: awong@marymount.edu
  • 11 Cancer Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Student Research Committee, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Electronic address: omid.asbaghi@gmail.com
Diabetes Metab Syndr, 2023 Aug;17(8):102824.
PMID: 37523928 DOI: 10.1016/j.dsx.2023.102824

Abstract

BACKGROUND AND AIM: It has been suggested that taking vitamin C supplements may improve glycemic control in patients with type 2 diabetes mellitus (T2DM). However, there has not been a thorough evaluation of the actual impact or certainty of the findings. This systematic review and meta-analysis was conducted to determine the effect of vitamin C supplementation on glycemic profile in T2DM patients.

METHODS: A systematic search was performed across online databases including Scopus, Web of Science, and PubMed/Medline to identify relevant randomized controlled trials (RCTs) published until July 2022. A random-effects model was applied for the meta-analysis.

RESULTS: The present meta-analysis included a total of 22 RCTs with 1447 patients diagnosed with T2DM.A pooled analysis revealed a significant decrease in levels of serum hemoglobin A1c (HbA1c), fasting insulin, and fasting blood glucose (FBG) in vitamin C-treated T2DM patients compared with their untreated counterparts. The dose-response evaluation displayed a substantial linear association between the intervention duration and changes in serum HbA1c levels. However, the analysis did not demonstrate any significant effect of vitamin C on serum values of homeostasis model assessment of insulin resistance(HOMA-IR) in diabetic patients. Subgroup analyses indicated that high-dose vitamin C administration (≥1000 mg/d) considerably decreased serum HOMA-IR levels.

CONCLUSION: These findings suggest that long-term (≥12 weeks) and high-dose vitamin C supplementation (≥1000 mg/d) may ameliorate glycemic profile in T2DM patients. However, additional high-quality RCTs are necessary to validate these results.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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