The DALI vitamin D randomized controlled trial for gestational diabetes mellitus prevention: No major benefit shown besides vitamin D sufficiency

Rosa Corcoy, Lilian C. Mendoza, David Simmons, Gernot Desoye, J. M. Adelantado, Ana Chico, Roland Devlieger, Andre van Assche, Sander Galjaard, Dirk Timmerman, Annunziata Lapolla, Maria G. Dalfra, Alessandra Bertolotto, J. rgen Harreiter, Ewa Wender-Ozegowska, Agnieszka Zawiejska, Alexandra Kautzky-Willer, Fidelma P. Dunne, Peter Damm, Elisabeth R. MathiesenDorte M. Jensen, Lise Lotte T. Andersen, Mette Tanvig, David J. Hill, Judith G. Jelsma, Frank J. Snoek, Harald Köfeler, Martin Trötzmüller, Paul Lips, Mireille N. M. van Poppel

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40 Citations (Scopus)


Background & aims: As vitamin D deficiency is associated with an increased risk of gestational diabetes mellitus (GDM), we aimed to test vitamin D supplementation as a strategy to reduce GDM risk (evaluated after fasting plasma glucose (FPG), insulin resistance and weight gain) in pregnant overweight/obese women. Methods: The DALI vitamin D multicenter study enrolled women with prepregnancy body mass index (BMI) ≥ 29 kg/m 2 , ≤19 + 6 weeks of gestation and without GDM. Participants were randomized to receive 1600 IU/day vitamin D3 or placebo (each with or without lifestyle intervention) on top of (multi)vitamins supplements. Women were 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. Results: 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, p < 0.001). 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. Conclusion: In the DALI vitamin D trial, supplementation with 1600 IU vitamin D3/day achieved vitamin D sufficiency in virtually all pregnant women and a small effect in FPG at 35–37 weeks. The potential of vitamin D supplementation for GDM prevention in vitamin D sufficient populations appears to be limited. Trial registration number: ISRCTN70595832
Original languageEnglish
Pages (from-to)976-984
Number of pages9
JournalClinical Nutrition
Issue number3
Early online date11 Apr 2019
Publication statusPublished - 1 Mar 2020


  • Fasting plasma glucose
  • Fasting plasma insulin
  • Gestational diabetes mellitus
  • Pregnancy
  • Vitamin D sufficiency
  • Vitamin D supplementation

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