Vitamin B₁₂ and gestational diabetes mellitus: a systematic review and meta-analysis

The relationship between vitamin B₁₂ and gestational diabetes mellitus (GDM) remains controversial. To comprehensively evaluate the relationship between vitamin B₁₂ and GDM, and to provide more information on GDM prevention, this study provides a systematic review and meta-analysis of vitamin B₁₂ and GDM. As of September 22, 2021, 304 articles were searched in PubMed, Web of Science, EMBASE, and Cochrane databases, of which 15 studies met the inclusion criteria. Results presented there was no association between maternal vitamin B₁₂ concentration during the first trimester with GDM, however, low vitamin B₁₂ concentration in the second or third trimester of pregnancy was related to an increased risk of GDM. Compared with the non-GDM group, the vitamin B₁₂ concentration in the GDM group was remarkably decreased (MD: -10·79; 95%CI: -21·37, -0·21), and vitamin B₁₂ deficiency increased the risk for GDM (OR: 1·59; 95%CI: 1·10, 2·29). These effects were more significant among Asians. In addition, an increased ratio of high folate to low vitamin B₁₂ in serum also increased the risk of GDM (OR: 1·87; 95% CI: 1·46, 2·41). These results suggest that more vitamin B₁₂ may need to be provided during pregnancy.