(HealthDay News) — The optimal 1-hour 50-g glucose challenge test screening cutoff for gestational diabetes is ≥135 mg/dL in twin pregnancies, according to a study published in the American Journal of Obstetrics & Gynecology.

Andrei Rebarber, MD, from the Icahn School of Medicine at Mount Sinai in New York City, and colleagues examined the ideal glucose challenge test cutoff in twin pregnancies undergoing gestational diabetes screening from a historical cohort of patients. 

Four hundred seventy-five patients underwent a 1-hour 50-g glucose challenge test at 24 to 28 weeks of gestation, and those with a glucose challenge test of ≥130 mg/dL underwent a 3-hour 100-g oral glucose tolerance test. 

The testing characteristics of the glucose challenge test for gestational diabetes diagnosis were assessed at cutoffs of ≥130 mg/dL, ≥135 mg/dL and ≥140 mg/dL.

The researchers found that the incidence of gestational diabetes was 6.5%. The positive screen rates were: ≥130 mg/dL, 34.%; ≥135 mg/dL, 28.6%; and ≥140, 23.4%. 

With a cutoff of ≥135 mg/dL, sensitivity and specificity were 100% and 76.4%, respectively. The positive and negative predictive values were 22.8% and 100%, respectively, at this cutoff. A cutoff of ≥135 mg/dL vs. ≥130 mg/dL resulted in 6.1% fewer patients testing positive, without affecting sensitivity.

“In twin pregnancies, the optimal one-hour 50-g GCT screening cut-off appears to be ≥135 mg/dL,” the researchers wrote.


  1. Rebarber A et al. Am J Obstet Gynecol. 2014;doi:10.1016/j.ajog.2014.08.030.