title: Vitamin C and the risk of gestational diabetes mellitus: a case-control study.
abstract: OBJECTIVE
  To examine whether low maternal dietary intake of vitamin C and low maternal plasma ascorbic acid (AA) concentrations are associated with an increased risk of gestational diabetes mellitus (GDM).
  
  
  METHODS
  Cases were 67 women with GDM meeting National Diabetes Data Group criteria. Controls were 260 women without such a diagnosis. Maternal dietary vitamin C consumption during the periconceptional period and during pregnancy was assessed using a 121-item, semiquantitative food frequency questionnaire. Maternal plasma AA concentrations were determined using automated enzymatic procedures on specimens collected during the intrapartum period.
  
  
  RESULTS
  Mean maternal daily consumption of vitamin C and plasma AA concentrations were 10% and 31% lower, respectively, among GDM cases as compared with controls (130.7 +/- 10.2 vs. 145 +/- 4.9 mg/d, P = .190; 36 +/- 2.0 vs. 53 +/- 1.0 micromol/L, P <.001). After controlling for maternal age, race, prepregnancy adiposity, family history of type 2 diabetes, energy intake and income, women reporting low daily vitamin C intake (< 70 mg/d), as compared with the other women, experienced a 3.7-fold increased risk of GDM (odds ratio [OR] = 3.7, 95% confidence interval [CI] 1.7-8.2). There was a linear relation in risk of GDM with decreasing concentrations of plasma AA (P for linear trend <.001). After adjusting for confounders, women in the lowest quartile (< 42.6 micromol/L), as compared with women in the highest quartile (> 63.3 micromol/L), experienced > 12-fold increased risk of GDM (OR = 12.8, 95% CI 3.5-46.2).
  
  
  CONCLUSIONS
  Low maternal dietary vitamin C intake and low plasma AA concentrations are associated with an increased risk of GDM. Large, prospective, cohort studies are needed to further evaluate the potential beneficial role of vitamin C and other antioxidants in the prevention of impaired glucose tolerance in pregnancy.
authors.affiliation: Department of Epidemiology, University of Washington School of Public Health and Community Medicine, Seattle, USA.
authors.forename: Cuilin
authors.initials: C
authors.lastname: Zhang
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Williams
authors.forename: Ihunnaya O
authors.initials: IO
authors.lastname: Frederick
authors.forename: Irena B
authors.initials: IB
authors.lastname: King
authors.forename: Tanya K
authors.initials: TK
authors.lastname: Sorensen
authors.forename: Mark M
authors.initials: MM
authors.lastname: Kestin
authors.forename: Edward E
authors.initials: EE
authors.lastname: Dashow
authors.forename: David A
authors.initials: DA
authors.lastname: Luthy
mesh_terms: D000293:Adolescent; D000328:Adult; D001205:Ascorbic Acid / Q000097:blood*; D001206:Ascorbic Acid Deficiency / Q000150:complications*; D016022:Case-Control Studies; D016640:Diabetes, Gestational / Q000209:etiology*; D005260:Female; D006801:Humans; D011247:Pregnancy; D012307:Risk Factors
chemical_list: D001205:Ascorbic Acid