SYSTEMATIC REVIEW article
Front. Nutr.
Sec. Clinical Nutrition
Assessing the Potency of Vitamin D Augmentation on Saccharometric Indices in Type 2 Diabetes: A Meta-Analysis
Provisionally accepted
Su Gong1
Li Chen2*- 1Zhuzhou Central Hospital, Zhuzhou, China
- 2Zhuzhou City Central Hospital, Zhuzhou, China
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Background: This meta-analytical investigation sought to elucidate the therapeutic efficacy and tolerability of vitamin D supplementation in modulating glycemic indices among individuals diagnosed with type 2 diabetes (T2D). Methods: Systematic searches were performed across PubMed, Embase, Web of Science, Cochrane Library, and Chinese databases (CNKI and Wanfang) to identify relevant randomized controlled trials (RCTs). Studies were deemed eligible if they enrolled adult T2D populations, administered vitamin D interventions, and reported outcomes including glycated hemoglobin (HbA1c), homeostasis model assessment of insulin resistance (HOMA-IR), or serum 25-hydroxyvitamin D [25(OH)D] concentrations. Results: Ten RCTs, encompassing a total of 3,460 participants, met inclusion criteria. Intervention durations varied between 3 and 12 months, and dosing regimens ranged from 500 IU and 60,000 IU. Pooled analysis revealed a significant increase in serum 25(OH)D levels following supplementation (SMD: 4.01; 95% CI: 2.43 to 5.59; p < 0.001; I² = 99.3%). In contrast, no statistically significant improvements were observed in HbA1c (SMD: 0.08; 95% CI: -0.25 to 0.37; p < 0.001; I² = 86.5%) or HOMA-IR (SMD: 5.95; 95% CI: -2.87 to 14.77; p < 0.001; I² = 100.0%). Adverse event profiles were similar between the vitamin D and control groups (RR: 1.19; 95% CI: 0.79 to 1.80; p = 0.183; I² = 43.5%). Conclusions: Vitamin D supplementation yield a consistent rise in serum 25(OH)D concentrations but exerts no discernible effect on glycemic regulation or insulin sensitivity in T2D populations. The favorable safety profile supports its tolerability. Considerable heterogeneity in metabolic outcomes underscores the need for future investigations stratified by baseline vitamin D status, enhancement regimen, and study duration.
Keywords: Vitamin D enhancement, Saccharometric indices, type 2 diabetes, glucose metabolism, Meta-analysis
Received: 26 Aug 2025; Accepted: 28 Nov 2025.
Copyright: © 2025 Gong and Chen. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Li Chen
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