The Effects of Serum Folic Acid and Vitamin B12 on the Risk of Gestational Diabetes Mellitus

PURPOSE: In order to gain more knowledge on the risk of gestational diabetes mellitus (GDM), and to provide evidence for clinical guidance on the optimum level of serum folic acid and vitamin B12, this study aimed to clarify the relationship between serum folic acid and vitamin B12 and the risk of GDM. PATIENTS AND METHODS: This retrospective case−control study was conducted based on the clinical information system of the Maternal and Child Health Hospital of Hubei Province. Clinical data including maternal socio-demographical characteristics, serum folic acid, and vitamin B12 were collected. Logistic regression analyses and restricted cubic splines were performed to examine the impact of serum folic acid and vitamin B12 on the risk of GDM. RESULTS: Significantly elevated risks of GDM were observed in groups with high serum folic acid concentration (OR = 1.84, 95% CI: 1.07−3.16), and in low vitamin B12 concentration (OR = 2.14, 95% CI: 1.26−3.65). After stratified by age, the increased risk of GDM was still noticed in a low level of vitamin B12 among mothers aged <30 years (OR = 4.76, 95% CI: 1.45−15.61). In mothers with pre−pregnancy BMI <24, elevated risk of GDM was significantly associated with a high folic acid (OR = 2.09, 95% CI: 1.11−3.93) or a low vitamin B12 concentration (OR = 2.24, 95% CI: 1.22−4.14). Moreover, the risk of GDM was on the decline with the increased level of folic acid in the beginning, and it started to manifest an upward trend when the serum folic acid reached 19.02 ng/mL. CONCLUSION: This study demonstrated that serum folic acid excess or vitamin B12 deficiency could contribute to the increased risk of GDM, and revealed the potential side effect of serum folic acid overdose. As serum folic acid and vitamin B12 tests are widely applied in clinical practice, this finding could help clinicians to evaluate maternal risk from a new perspective.