Vitamin D and Gestational Diabetes Mellitus: A Systematic Review Based on Data Free of Hawthorne Effect

BJOG. 2018 Jun;125(7):784-793. doi: 10.1111/1471-0528.15060. Epub 2018 Jan 18.


Background: Gestational diabetes mellitus (GDM) is an increasingly prevalent disorder, associated with low blood vitamin D level.

Objectives: To evaluate the relationship between vitamin D and GDM.

Search strategy: EMBASE, MEDLINE, Cochrane Library and China Biology Medicine disc were searched up to May 2017. The references of previous studies were screened.

Selection criteria: Observational studies on the relationship between vitamin D and GDM free from Hawthorne effect and randomised controlled trials of vitamin D supplementation during pregnancy for preventing or treating GDM were included.

Data collection and analysis: Data and information of included articles were extracted by duplicate using piloted tables. Newcastle-Ottawa Scale and Cochrane Handbook were used for quality assessment. Random-effects models were used for meta-analyses. Heterogeneity tests, sensitivity analysis and analysis of publication bias were conducted.

Main results: Eighty-seven observational studies and 25 randomised controlled trials involving 55 859 and 2445 women, respectively, were included. Low blood vitamin D level during pregnancy was associated with a higher risk of GDM (OR 1.850, 95% CI 1.471-2.328). Blood vitamin D level for women with GDM were lower than in the control women. Blood vitamin D level was associated with fasting plasma glucose (FPG) and homeostasis model of assessment for insulin resistance index (HOMA-IR) (r = -0.100 and r = -0.351), whereas the correlation between blood vitamin D level and fasting insulin (FINS) might be concealed by publication bias. Vitamin D intervention during pregnancy could change the blood levels of vitamin D, FINS, FPG, HOMA-IR, glutathione, C-reactive protein and lipid.

Conclusions: Low blood vitamin D level could increase the risk of GDM, and vitamin D supplementation during pregnancy could ameliorate the condition of GDM.

Tweetable abstract: Low blood vitamin D increases gestational diabetes mellitus (GDM) risk. Vitamin D supplementation ameliorates GDM condition.

Keywords: blood glucose; gestational diabetes mellitus; insulin; meta-analysis; vitamin D.

Publication types

  • Systematic Review

MeSH terms

  • Blood Glucose / analysis
  • Diabetes, Gestational / etiology*
  • Diabetes, Gestational / therapy
  • Dietary Supplements
  • Fasting / blood
  • Female
  • Humans
  • Insulin / blood
  • Insulin Resistance
  • Observational Studies as Topic
  • Pregnancy
  • Pregnancy Trimesters / blood*
  • Randomized Controlled Trials as Topic
  • Risk Factors
  • Vitamin D / blood*
  • Vitamin D / therapeutic use
  • Vitamin D Deficiency / blood
  • Vitamin D Deficiency / complications*


  • Blood Glucose
  • Insulin
  • Vitamin D