The Effect of Vitamin D Supplementation on Glycaemic Control in Women with Gestational Diabetes Mellitus: A Systematic Review and Meta-Analysis of Randomised Controlled Trials
What this study found
Vitamin D supplementation during pregnancy was associated with better glycaemic control in women with gestational diabetes, with improvements seen most consistently in fasting blood glucose, glycated haemoglobin, and serum insulin. Individual trials reported significant reductions in fasting glucose, such as -17.12 ± 14.84 vs -0.96 ± 16.64 mg/dL (p < 0.001) and -9.9 ± 7.2 vs 2.9 ± 7.6 mg/dL (p = 0.04), and some trials also showed lower HbA1c, including -0.18% ± 0.48% vs 0.17% ± 0.39% (p = 0.02). However, results were not uniform across all studies or outcomes, with some insulin and glucose…
- Study & population
- Systematic review and meta-analysis of 5 randomized controlled trials conducted in Iran and China.
- Intervention
- Vitamin D supplementation during pregnancy was evaluated in several randomized trials among women with gestational diabetes mellitus, using a range of regimens including oral vitamin D3 capsules, vitamin D3-fortified yogurt, and a single intramuscular vitamin D dose.
- Key limitation
- The evidence base was limited to 5 randomized trials, with all studies conducted in Iran or China, which restricts generalizability.
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Open PDFOriginal abstract
Vitamin D deficiency is highly prevalent amongst pregnant women and is linked to a range of adverse complications, including gestational diabetes. However, there is no consensus among researchers regarding the impact of vitamin D supplementation in alleviating adverse effects in gestational diabetes. The objective of this systematic review and meta-analysis was to determine whether supplementation of vitamin D given to women with gestational diabetes can promote glycaemic control. EMBASE and PubMed were searched up to November, 2018. The selection criteria included randomised controlled trials of the effect of vitamin D supplementation (1000–4762 IU/day) on pregnant women with gestational diabetes mellitus. Study data and outcome measures (fasting blood glucose, glycated haemoglobin and serum insulin) were extracted from included studies. Random-effects models were used for meta-analyses. Heterogeneity tests, and analysis of the risk of bias were conducted. Most of the studies were graded as having either low risk or moderate risk of bias although two studies had a high risk of bias in the areas of blinding of participants and personnel, and incomplete outcome data. On the other hand, the heterogeneity statistic (I2) ranged from 0–41% in the studies included. Five randomised controlled trials were selected for this review and meta-analysis (involving a total of 173 participants supplemented with vitamin D and 153 participants as control drawn from the studies). Vitamin D supplementation was associated with a decrease in fasting blood glucose by a mean of 0.46 mmol/L (−0.68, −0.25) (p < 0.001), glycated haemoglobin by a mean of 0.37% (−0.65, −0.08) (p < 0.01) and serum insulin concentration by mean of 4.10 µIU/mL (−5.50, −2.71) (p < 0.001) compared to controls. This review shows evidence that vitamin D supplementation has the potential to promote glycaemic control in women with Gestational Diabetes Mellitus (GDM). However, due to the limited number of studies in the meta-analysis, the conclusion should be interpreted with caution. Further studies are needed to fully understand the exact mechanism by which vitamin D influences glucose metabolism.