Association of maternal folate and B12 vitamin status with gestational diabetes mellitus: Still an open issue

Objectives: There is conflicting evidence about the role of folate and B12 in gestational diabetes mellitus (GDM) onset. The association of vitamin status with GDM was therefore revalued, also measuring the B12 active form holotranscobalamin. Methods: 677 women were evaluated at 24–28 weeks of gestation when OGTT was carried out. The ‘one-step’ strategy was employed for GDM diagnosis. Odds ratio (OR) of having GDM was estimated to quantify the association with vitamin levels. Results: 180 women (26.6%) had GDM. They were older (median, 34.6 vs. 33.3 years, p = 0.019) and had higher body mass index (BMI) (25.8 vs. 24.1 kg/m2 , p < 0.001). Multiparous women had lower levels of all evaluated micronutrients, while overweight lowered both folate and total B12, but not holotranscobalamin. Lower total B12 (270 vs. 290 ng/L, p = 0.005), but not holotranscobalamin, was observed in GDM, being weakly negatively correlated with fasting glycemia (r = − 0.11, p = 0.005) and 1-h OGTT serum insulin (r = − 0.09, p = 0.014). At multivariate analysis, age, BMI and multiparity remained the strongest GDM predictors, while total B12 (but not holotranscobalamin and folate) showed a slight protective effect (OR = 0.996, p = 0.038). Conclusions: A weak association between total B12 levels and GDM risk was shown, but it was not confirmed when holotranscobalamin was measured.