ORIGINAL RESEARCH article
Front. Endocrinol.
Sec. Developmental Endocrinology
Predictive Value of OGTT Parameters and Clinical Markers in Gestational Diabetes Mellitus: A Prospective Randomized Controlled Trial from a Tertiary Center in Türkiye
Batuhan Turgay 1,2
Uğurcan Zorlu 3
Harun Kılıçkıran 4
Kayra Turgay 5
Gülşah Aynaoğlu 1
A.Seval Ozgu-Erdinc 3
1. Ankara Universitesi Tip Fakultesi, Ankara, Türkiye
2. Reproductive Health Diagnosis Treatment Education Research and Application Center, Ankara University, Ankara, Türkiye
3. TC Saglik Bakanligi Ankara Sehir Hastanesi, Çankaya, Türkiye
4. Dörtyol State Hospital, Hatay, Türkiye
5. Gazi Universitesi Tip Fakultesi, Ankara, Türkiye
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Abstract
Background: Gestational diabetes mellitus (GDM) remains a major obstetric concern, yet the optimal screening strategy and the prognostic value of oral glucose tolerance test (OGTT) parameters remain debated. We aimed to compare the diagnostic yield and clinical outcomes of a two-step OGTT strategy (50 g glucose challenge followed by 100 g OGTT) versus a one-step 75 g OGTT approach, and to evaluate the predictive performance of individual OGTT time points for pregnancy complications and treatment requirement. Methods: In this prospective randomized controlled trial, 1,439 pregnant women undergoing routine screening at 24–28 weeks of gestation were randomized to either a two-step OGTT strategy (n=719) or a one-step 75 g OGTT strategy (n=720). GDM was classified as diet-controlled or insulin-requiring. Maternal risk factors, obstetric outcomes, and neonatal outcomes were recorded. Receiver operating characteristic (ROC) analyses assessed the predictive ability of OGTT parameters for polyhydramnios and insulin requirement. Results: Overall GDM prevalence was 12.3%, including 8.4% diet-controlled and 3.9% insulin-requiring cases. The one-step strategy identified a numerically higher proportion of GDM without significant differences in maternal or neonatal outcomes compared with the two-step approach. Rates of polyhydramnios, hypertensive disorders, macrosomia, cesarean delivery, preterm birth, neonatal intensive care admission, small for gestational age (7.4%), and intrauterine growth restriction (4.2%) were comparable between groups. ROC analyses demonstrated that 2-hour OGTT values showed the strongest predictive performance for polyhydramnios (AUC up to 0.816) and insulin requirement (AUC up to 0.808), whereas the 50 g screening test showed only moderate discrimination. Conclusion: The one-step 75 g OGTT increases diagnostic labeling without improving short-term clinical outcomes. Post-load OGTT values—particularly 2-hour glucose levels—provide the most clinically meaningful prognostic information and may support a risk-stratified approach to GDM management rather than expansion of diagnostic thresholds alone.
Summary
Keywords
gestational diabetes mellitus, insulin therapy, Oral glucose tolerance test, Polyhydramnios, randomized controlled trial, risk stratification, ROC analysis
Received
26 January 2026
Accepted
17 February 2026
Copyright
© 2026 Turgay, Zorlu, Kılıçkıran, Turgay, Aynaoğlu and Ozgu-Erdinc. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Batuhan Turgay
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