Joint effects of folate and vitamin B12 imbalance with maternal characteristics on gestational diabetes mellitus.

BACKGROUND: The purpose of this study was to examine whether folate and vitamin B12 imbalance is associated with gestational diabetes mellitus (GDM) and to explore the interaction effects between B-vitamin imbalance and maternal risk factors for GDM.

METHODS: A cross-sectional study with 406 participants was performed in a Chinese population. Serum folate, vitamin B12, and blood glucose levels were measured at 24 to 28 weeks' gestation during GDM screening. GDM was diagnosed according to the criteria of the International Association of Diabetes and Pregnancy Study Groups (fasting plasma glucose ≥ 5.1 mmol/L, 1-hour plasma glucose ≥ 10.0 mmol/L, or 2-h plasma glucose ≥ 8.5 mmol/L). Binary logistic regression was used to obtain odds ratios (ORs) by controlling for different confounders, respectively.

RESULTS: Higher folate levels were associated with higher glucose concentrations and higher risk of GDM (OR: 1.98 [1.00, 3.90]), while higher vitamin B12 levels were associated with lower fasting plasma glucose and lower risk of GDM (OR: 0.30 [0.15, 0.60]). Higher folate/B12 was associated with higher glucose and higher risk of GDM (OR: 3.08 [1.63, 5.83]). The presence of both higher folate/B12 and advanced age further increased the OR to 2.13 (95% confidence interval: 1.09-4.15) with significant additive interaction. Furthermore, higher folate/B12 and higher prepregnancy body mass index (pp-BMI) were synergistically associated with increased risk of GDM (OR: 3.03 [1.40, 6.57]).

CONCLUSIONS: Imbalance of folate and vitamin B12, represented as higher folate/B12, was highly associated with GDM risk, and this association can be further modified by maternal age and pp-BMI.