Background: Vitamin K supplementation was shown to be effective on glucose hemostasis and insulin sensitivity in some previous studies, but the results are controversial. The purpose of this meta-analysis was to investigate the effect of vitamin K supplementation on glycemic indices including fasting blood sugar (FBS), hemoglobin A1c (HbA1c), fasting insulin (FI), homeostatic model assessment for insulin resistance (HOMA-IR), quantitative insulin-sensitivity check index (QUICKI) and homeostasis model assessment of β-cell function (HOMA-β).
Methods: The systematic search of literatures was performed on electronic databases of PubMed, Scopus, and Web of Science databases up to December, 2024. The weighted mean difference (WMD) and 95% confidence intervals (95% CI) were calculated to evaluate the pooled effect size using the random-effect model. The heterogeneity was evaluated using I-square (I2) statistics. Subgroup analysis was done to evaluate the potential sources of heterogeneity.
Results: Among all of the eligible studies, six randomized clinical trials (RCTs) were included in this meta-analysis. The results showed a significant effect of vitamin K supplementation on some glycemic indices including FI (WMD: -1.87; 95% CI: -2.64, -1.09), HbA1c (WMD: -0.89; 95% CI: -1.40, -0.38) and HOMA-IR (WMD: -0.35; 95% CI: -0.39, -0.31).
Also, the effect of vitamin K supplementation on other glycemic indices including FBS (WMD: -4.74; 95% CI: -10.56, 1.09), HOMA-β (WMD: -0.36; 95% CI: -1.44, 0.73) were not a significant effect.
Conclusion: The findings of this study indicated that vitamin K supplementation can positively affect FI, HbA1c, and HOMA-IR levels.