title: Maternal Midpregnancy Glucose Levels and Risk of Congenital Heart Disease in Offspring.
abstract: OBJECTIVE
  There is a well-described association between maternal diabetes mellitus and risk of congenital heart disease (CHD) in offspring. Although the clinical diagnoses of type 2 diabetes or gestational diabetes are strong risk factors for CHD, subclinical abnormalities of glucose and insulin metabolism are common within the general population and could also confer risk for CHD. We hypothesize that continuous measures of blood analytes related to maternal diabetes are related to odds of cardiac malformations.
  
  
  OBJECTIVE
  To explore the potential association of 2 different CHD phenotypes in offspring with maternal midpregnancy measures of glucose and insulin.
  
  
  METHODS
  Case-control study from a population-based cohort of 277 pregnant women in southern and central California carrying infants with tetralogy of Fallot (TOF) (n = 55), dextrotransposition of the great arteries (dTGA) (n = 42), or healthy infants without CHD (n = 180). Serum samples were collected from 2003 through 2007. The analysis was conducted from March through June 2015.
  
  
  METHODS
  Blood analytes related to maternal glucose metabolism were measured from random nonfasting second-trimester blood samples. We measured serum insulin levels by a validated radioimmunoassay, and we measured glucose levels. Multivariable logistic regression models estimated the association between these levels and case status.
  
  
  RESULTS
  Serum glucose values were elevated in the maternal samples for offspring with TOF (median, 97.0 mg/dL [to convert to millimoles per liter, multiply by 0.0555]) relative to controls (median, 91.5 mg/dL) (P = .01, Wilcoxon rank sum test), a phenomenon not observed in the maternal samples for offspring with dTGA (median, 90.0 mg/dL) relative to controls (P = .18, Wilcoxon rank sum test). Serum insulin levels were significantly different between controls (median, 18.8 μIU/mL [to convert to picomoles per liter, multiply by 6.945]) and maternal samples for offspring with dTGA (median, 13.1 μIU/mL; P = .048, Wilcoxon rank sum test) but not with TOF (median, 14.3 μIU/mL; P = .35, Wilcoxon rank sum test). Relative to maternal blood glucose levels of infants without cardiac malformations, we observed that maternal blood glucose levels in models including insulin were strongly associated with odds of TOF (adjusted odds ratio = 7.54; 95% CI, 2.30-24.69) but not with dTGA (adjusted odds ratio = 1.16; 95% CI, 0.28-4.79).
  
  
  CONCLUSIONS
  These results represent a direct correlation of glucose as a continuous variable to odds of specific cardiac malformations. The association between serum glucose and odds of TOF indicates the need for additional epidemiological and mechanistic investigations into the risk conferred by insulin signaling and glucose metabolism during early pregnancy.
authors.affiliation: Stanford Cardiovascular Institute, Division of Pediatric Cardiology, Stanford University School of Medicine, Stanford, California.
authors.forename: James R
authors.initials: JR
authors.lastname: Priest
authors.affiliation: Department of Pediatrics, Stanford University School of Medicine, Stanford, California.
authors.forename: Wei
authors.initials: W
authors.lastname: Yang
authors.affiliation: Stanford Cardiovascular Institute, Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, California.
authors.forename: Gerald
authors.initials: G
authors.lastname: Reaven
authors.affiliation: Stanford Cardiovascular Institute, Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, California.
authors.forename: Joshua W
authors.initials: JW
authors.lastname: Knowles
authors.affiliation: Department of Pediatrics, Stanford University School of Medicine, Stanford, California.
authors.forename: Gary M
authors.initials: GM
authors.lastname: Shaw
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000032:analysis*; D002140:California; D016022:Case-Control Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood*; D016640:Diabetes, Gestational / Q000097:blood*; D005260:Female; D006330:Heart Defects, Congenital / Q000453:epidemiology* / Q000209:etiology; D006801:Humans; D007328:Insulin / Q000097:blood; D016017:Odds Ratio; D011247:Pregnancy; D012307:Risk Factors; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D007328:Insulin