It is very uncertain whether vitamin D + calcium + other vitamins and minerals changes gestational diabetes compared with calcium + other vitamins and minerals (but no vitamin D) (very low certainty).
Meta-analysis of observational studies (higher vs lower maternal 25(OH)D) for Gestational diabetes: OR 0.67 (95% CI 0.53 to 0.85), statistically significant. Umbrella review outcome-level evidence grade: Suggestive.
Vitamin D supplementation probably leads to lower gestational diabetes compared with placebo or no intervention (moderate certainty).
It is very uncertain whether vitamin D + calcium supplementation changes gestational diabetes compared with placebo or no intervention (very low certainty).
A dose of vitamin D 601 IU or higher probably leads to lower gestational diabetes compared with 600 IU or lower alone or with other nutrients (moderate certainty).
A dose of vitamin D 4000 IU/d or more showed no clear difference in gestational diabetes compared with 3999 IU/d or less alone or with any other nutrient (low certainty).