title: Screening approach for gestational diabetes in twin pregnancies.
abstract: OBJECTIVE
  The objective of this study was to evaluate the ideal cutoff for the glucose challenge test (GCT) in twin pregnancies undergoing screening for gestational diabetes mellitus (GDM).
  
  
  METHODS
  A historical cohort of patients with twin pregnancies were identified from 1 maternal-fetal medicine practice from 2005 through 2013. All patients were administered a 1-hour, 50-g GCT between 24-28 weeks' gestation. All patients with a GCT of ≥130 mg/dL underwent a 3-hour, 100-g oral glucose tolerance test. The diagnosis of GDM was made if 2 of the 4 values on the oral glucose tolerance test were abnormal (Carpenter and Coustan). The testing characteristics of the GCT for diagnosis of GDM were evaluated using 3 selected cutoffs: ≥130, ≥135, and ≥140 mg/dL. We excluded all patients diagnosed with GDM <24 weeks.
  
  
  RESULTS
  In all, 475 patients with twin pregnancies underwent a GCT between 24-28 weeks. The incidence of GDM was 6.5%. The positive screen rate using the 3 selected cutoffs were: ≥130 mg/dL, 34.7%; ≥135 mg/dL, 28.6%; and ≥140 mg/dL, 23.4%. A GCT cutoff of ≥135 mg/dL maintained 100% sensitivity, with a specificity of 76.4%. Using this cutoff, the positive predictive value was 22.8% and the negative predictive value was 100%. Compared to a cutoff of ≥130 mg/dL, a cutoff of ≥135 mg/dL resulted in 6.1% less patients testing positive while maintaining the same 100% sensitivity.
  
  
  CONCLUSIONS
  In twin pregnancies, the optimal 1-hour, 50-g GCT screening cutoff appears to be ≥135 mg/dL.
authors.affiliation: Maternal Fetal Medicine Associates PLLC, New York, NY; Department of Obstetrics, Gynecology, and Reproductive Science, Icahn School of Medicine at Mount Sinai, New York, NY.
authors.forename: Andrei
authors.initials: A
authors.lastname: Rebarber
authors.affiliation: Department of Obstetrics and Gynecology, New York University School of Medicine, New York, NY.
authors.forename: Cara
authors.initials: C
authors.lastname: Dolin
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Science, Icahn School of Medicine at Mount Sinai, New York, NY.
authors.forename: Jessica C
authors.initials: JC
authors.lastname: Fields
authors.affiliation: Maternal Fetal Medicine Associates PLLC, New York, NY; Department of Obstetrics, Gynecology, and Reproductive Science, Icahn School of Medicine at Mount Sinai, New York, NY.
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Saltzman
authors.affiliation: Maternal Fetal Medicine Associates PLLC, New York, NY; Department of Obstetrics, Gynecology, and Reproductive Science, Icahn School of Medicine at Mount Sinai, New York, NY.
authors.forename: Chad K
authors.initials: CK
authors.lastname: Klauser
authors.affiliation: Maternal Fetal Medicine Associates PLLC, New York, NY; Department of Obstetrics, Gynecology, and Reproductive Science, Icahn School of Medicine at Mount Sinai, New York, NY.
authors.forename: Simi
authors.initials: S
authors.lastname: Gupta
authors.affiliation: Maternal Fetal Medicine Associates PLLC, New York, NY; Department of Obstetrics, Gynecology, and Reproductive Science, Icahn School of Medicine at Mount Sinai, New York, NY. Electronic address: nfox@mfmnyc.com.
authors.forename: Nathan S
authors.initials: NS
authors.lastname: Fox
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D015331:Cohort Studies; D016640:Diabetes, Gestational / Q000175:diagnosis*; D005260:Female; D005951:Glucose Tolerance Test / Q000379:methods; D006801:Humans; D011237:Predictive Value of Tests; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D059285:Pregnancy, Twin; D011296:Prenatal Diagnosis; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D001786:Blood Glucose
keywords: gestational diabetes; glucose challenge test; glucose tolerance test; twins