Vitamin D plays minimal role in prevention of gestational diabetes

Gestational diabetes mellitus is a condition in which a woman develops high blood sugar levels due to impaired glucose metabolism during pregnancy. GDM predisposes the fetus to various adverse effects. Moreover, GDM increases the mother’s risk of developing type 2 diabetes later in life.

The present study enrolled women with prepregnancy body mass index (BMI) ≥ 29 kg/m², ≤19 + 6 weeks of gestation and without GDM. They were randomized to receive 1600 IU/day vitamin D3 or placebo (each with or without lifestyle intervention) on top of (multi)vitamins supplements. The women were then assessed for vitamin D status (sufficiency defined as serum 25-hydroxyvitamin D (25(OH)D) ≥ 50 nmol/l), FPG, insulin resistance and weight at baseline, 24–28 and 35–37 weeks. Linear or logistic regression analyses were performed to assess intervention effects.

• Average baseline serum 25(OH)D was ≥50 nmol/l across all study sites.


• In the vitamin D intervention arm (n = 79), 97% of participants achieved target serum vitamin 25(OH)D (≥50 nmol/l) at 24–28 weeks and 98% at 35–37 weeks vs 74% and 78% respectively in the placebo arm (n = 75).


• A small but significantly lower FPG (−0.14 mmol/l; CI95 −0.28, −0.00) was observed at 35–37 weeks with the vitamin D intervention without any additional difference in metabolic status, perinatal outcomes or adverse event rates.