title: Association between serum 25-hydroxyvitamin D in early pregnancy and risk of gestational diabetes mellitus.
abstract: OBJECTIVE
  There is emerging evidence of a relationship between vitamin D insufficiency and glucose intolerance. The aim of this study was to determine whether low serum 25-hydroxyvitamin D in early pregnancy is associated with an increased risk of gestational diabetes mellitus.
  
  
  METHODS
  This nested case-control study examined the association between serum 25-hydroxyvitamin D and risk of gestational diabetes within a cohort of pregnant women from March 2008 to December 2009, who had undergone antenatal screening between 15 and 18 weeks gestation and subsequent glucose tolerance testing. Cases were women diagnosed with gestational diabetes and each case was matched to up to two controls without gestational diabetes on age, race and date of blood collection. Serum 25-hydroxyvitamin D was measured from stored antenatal screening samples and compared between cases and controls.
  
  
  RESULTS
  Of the 116 women with gestational diabetes and 219 control subjects studied, the average age was 34.3 years and 41% were of non-Caucasian race. Women with gestational diabetes had significantly lower serum 25-hydroxyvitamin D compared with control subjects (56.3 vs. 62.0 nmol/l, P = 0.018). After adjusting for gestational age and maternal weight, serum 25-hydroxyvitamin D below the top quartile (< 73.5 nmol/l) was associated with a twofold greater likelihood of gestational diabetes (adjusted odds ratio 2.21, 95% confidence interval 1.19-4.13).
  
  
  CONCLUSIONS
  Lower vitamin D status in early pregnancy was associated with a significantly increased risk of subsequent gestational diabetes that was independent of race, age, season and maternal weight. This study suggests that vitamin D may influence glucose tolerance during pregnancy and provides support for studies of vitamin D as a potential intervention to prevent gestational diabetes.
authors.affiliation: Faculty of Medicine, University of Toronto, Toronto, ON, Canada.
authors.forename: L
authors.initials: L
authors.lastname: Parlea
authors.forename: I L
authors.initials: IL
authors.lastname: Bromberg
authors.forename: D S
authors.initials: DS
authors.lastname: Feig
authors.forename: R
authors.initials: R
authors.lastname: Vieth
authors.forename: E
authors.initials: E
authors.lastname: Merman
authors.forename: L L
authors.initials: LL
authors.lastname: Lipscombe
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D015331:Cohort Studies; D016640:Diabetes, Gestational / Q000097:blood* / Q000517:prevention & control; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D018570:Risk Assessment; D012307:Risk Factors; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood / Q000627:therapeutic use; D014808:Vitamin D Deficiency / Q000097:blood* / Q000150:complications
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D