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Optimal gestational diabetes screening threshold identified for twin pregnancies
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The optimal first step blood glucose cutoff for additional gestational diabetes screening has, for the first time, been identified for twin pregnancies, according to research published in the American Journal of Obstetrics & Gynecology.
“In twin pregnancy, the ideal cutoff for the glucose challenge test appears to be ≥135 mg/dL,” Nathan S. Fox, MD, of the Icahn School of Medicine at Mount Sinai, told Endocrine Today.
Nathan S. Fox
This screening cutoff for a 1-hour, 50-g glucose challenge test (GCT) falls between the 130 mg/dL to 140 mg/dL range with variable sensitivities and specificities that have been typically reported, according to the study.
Fox, along with Andrei Rebarber, MD, also of Mount Sinai, and colleagues from that institution and New York University School of Medicine looked at a historical cohort of 475 patients with twin pregnancies identified from a single maternal-fetal medicine practice between 2005 and 2013; those diagnosed with gestational diabetes at <24 weeks were excluded.
All women were given a 1-hour, 50-g GCT between 24 and 28 weeks of gestation. Women with a GCT of ≥130 mg/dL were given a 3-hour, 100-g oral glucose tolerance test. If two of the four values on the OGTT were abnormal, a diagnosis of gestational diabetes was made. GCT testing characteristics to diagnose gestational diabetes were evaluated at ≥130 mg/dL, ≥135 mg/dL and ≥140 mg/dL.
The incidence of gestational diabetes was 6.5%. The positive screening rate based on the three selected cutoffs were: ≥130 mg/dL, 34.7%; ≥135 mg/dL, 28.6%; and ≥140 mg/dL, 23.4%. The cutoff of ≥135 mg/dL maintained 100% sensitivity and a specificity of 76.4%; the positive predictive value was 22.8% and the negative predictive value was 100%.
The cutoff of ≥135 mg/dL resulted in 6.1% fewer patients testing positive than the cutoff of ≥130 mg/dL and maintained the same 100% sensitivity.
“Future research should focus on the ideal approach to gestational diabetes screening in twin pregnancies,” Fox said. “More importantly, future research needs to focus on the relative benefits of diagnosis and treatment of gestational diabetes in twin pregnancies overall as current recommendations are based on data from singleton pregnancies.” – by Allegra Tiver
For more information:
Nathan S. Fox, MD, can be reached at Maternal Fetal Medicine Associates,
70 E. 90th St., New York, NY 10021; website: www.mfmnyc.com.
Disclosure: The researchers report no relevant financial disclosures.
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