The relationship between vitamin K and T2DM: a systematic review and meta-analysis

Background: Previous studies have shown the potential role of vitamin K supplementation in the prevention and treatment of many diseases. However, the effect of vitamin K supplementation on blood glucose remains controversial. The purpose of this study was to assess the effects of vitamin K supplementation on glycemia-related indicators, including Fasting Blood Sugar (FBS), Fasting Insulin (FINS) and Homeostasis Model Assessment of Insulin Resistance (HOMA-IR). The potential association between vitamin K and type 2 diabetes mellitus (T2DM) risk was also evaluated. Methods: Up to April 2023, Cochrane, PubMed, Web of Science, Medline and EMBASE databases were searched to assess the effects of vitamin K on blood glucose and the risk of developing T2DM. Results: A meta-analysis of seven studies (813 participants) found vitamin K supplementation significantly reduced FBS (SMD = -0.150 mg dl^-1, 95% CI = -0.290, -0.010 mg dl^-1) and HOMA-IR (SMD = -0.200, 95% CI = -0.330, -0.060), but not FINS. Five studies with a total of 105 798 participants were included in the meta-analysis of the association between vitamin K and T2DM. The results showed that vitamin K was associated with the reduced risk of developing T2DM (HR = 0.79, 95% CI [0.71-0.88], P < 0.001). Conclusion: The meta-analysis demonstrated that vitamin K supplementation had a significant effect on the regulation of FBS and HOMA-IR in the population. Moreover, vitamin K was associated with the reduced risk of developing T2DM. Considering some limitations found in this study, additional data from large clinical trials are needed.