• This study was designed to test the hypothesis that low plasma vitamin B12 concentrations combined with high folate concentrations in pregnancy are associated with a higher incidence of gestational diabetes (GDM) and later diabetes
• Women (N = 785) attending the antenatal clinics of one hospital in Mysore, India, had their anthropometry, insulin resistance (homeostasis model assessment-2) and glucose tolerance assessed at 30 weeks’ gestation and at 5 years after delivery. Gestational vitamin B12 and folate concentrations were measured in plasma samples.
• Low vitamin B12 concentrations (<150 pmol/l, B12 deficiency) were observed in 43% of women and low folate concentrations (<7 nmol/l) in 4%.
• B12-deficient women had higher body mass index, sum of skinfold thickness insulin resistance and a higher incidence of GDM than non-deficient women. Vitamin B12 deficiency during pregnancy was also associated with skinfold thickness, insulin resistance and diabetes prevalence at 5 year follow-up.
• The impact of having both low vitamin B12 and high folate was particularly dramatic increasing GDM risk by 97%. The exact mechanism linking high folate, low B12 with glucose intolerance and insulin resistance remains unclear. This finding has potential implications for antenatal supplement recommendations but will require confirmation in future studies.
• The association with diabetes became non-significant after excluding women with previous GDM.
• Conclusions: maternal vitamin B12 deficiency is associated with increased adiposity and, in turn, with insulin resistance and GDM. Vitamin B12 deficiency may be an important factor underlying the high risk of ‘diabesity’ in south Asian Indians.
Lai JS et al. High folate and low vitamin B12 status during pregnancy is associated with gestational diabetes mellitus. Clin Nutr. 2017 Mar 24. pii: S0261-5614(17)30113-9. doi: 10.1016/j.clnu.2017.03.022. [Epub ahead of print]