Oral Glucose-Lowering Agents vs Insulin for Gestational Diabetes
Authors: Rademaker Doortje , de Wit Leon , Duijnhoven Ruben G. , Voormolen Daphne N. , Mol Ben Willem , Franx Arie , DeVries J. Hans , Painter Rebecca C. , van Rijn Bas B. ,   SUGAR-DIP Study Group, Siegelaar Sarah E. , Akerboom Bettina M. C. , Kiewiet-Kemper Rosalie M. , Verwij-Didden Marion A. L. , Assouiki Fahima , Kuppens Simone M. , Oosterwerff Mirjam M. , Stekkinger Eva , Diekman Mattheus J. M. , Vogelvang Tatjana E. , Belle–van Meerkerk Gerdien , Galjaard Sander , Verdonk Koen , Lub Annemiek , Klooker Tamira K. , Krabbendam Ineke , van Wijk Jeroen P. H. , Huisjes Anjoke J. M. , van Bemmel Thomas , Nijman Remco G. W. , van den Beld Annewieke W. , Hermes Wietske , Johannsson-Vidarsdottir Solrun , Vlug Anneke G. , Dullemond Remke C. , Jansen Henrique J. , Sueters Marieke , de Koning Eelco J. P. , van Laar Judith O. E. H. , Wouters–van Poppel Pleun , Evers Inge M. , Sanson–van Praag Marina E. , van den Akker Eline S. , Brouwer Catherine B. , Hermsen Brenda B. , Scholten Ralph , Meijer Rick I. , van Leeuwen Marsha , Wijbenga Johanna A. M. , Wijnberger Lia D. E. , van Bon Arianne C. , van der Made Flip W. , Eskes Silvia A. , Zandstra Mirjam , van Houtum William H. , Braams-Lisman Babette A. M. , Daemen-Gubbels Catharina R. G. M. , Nijkamp Janna W. , de Valk Harold W. , Wouters Maurice G. A. J. , IJzerman Richard G. , Reiss Irwin , van der Post Joris A. M. , Bosmans Judith E. 
Published: January 2025

Importance

Metformin and glyburide monotherapy are used as alternatives to insulin in managing gestational diabetes. Whether a sequential strategy of these oral agents results in noninferior perinatal outcomes compared with insulin alone is unknown.

Objective

To test whether a treatment strategy of oral glucose-lowering agents is noninferior to insulin for prevention of large-for-gestational-age infants.

Design, Setting, and Participants

Randomized, open-label noninferiority trial conducted at 25 Dutch centers from June 2016 to November 2022 with follow-up completed in May 2023. The study enrolled 820 individuals with gestational diabetes and singleton pregnancies between 16 and 34 weeks of gestation who had insufficient glycemic control after 2 weeks of dietary changes (defined as fasting glucose &amp;gt;95 mg/dL [&amp;gt;5.3 mmol/L], 1-hour postprandial glucose &amp;gt;140 mg/dL [&amp;gt;7.8 mmol/L], or 2-hour postprandial glucose &amp;gt;120 mg/dL [&amp;gt;6.7 mmol/L], measured by capillary glucose self-testing).

Interventions

Participants were randomly assigned to receive metformin (initiated at a dose of 500 mg once daily and increased every 3 days to 1000 mg twice daily or highest level tolerated; n = 409) or insulin (prescribed according to local practice; n = 411). Glyburide was added to metformin, and then insulin substituted for glyburide, if needed, to achieve glucose targets.

Main Outcomes and Measures

The primary outcome was the between-group difference in the percentage of infants born large for gestational age (birth weight &amp;gt;90th percentile based on gestational age and sex). Secondary outcomes included maternal hypoglycemia, cesarean delivery, pregnancy-induced hypertension, preeclampsia, maternal weight gain, preterm delivery, birth injury, neonatal hypoglycemia, neonatal hyperbilirubinemia, and neonatal intensive care unit admission.

Results

Among 820 participants, the mean age was 33.2 (SD, 4.7) years). In participants randomized to oral agents, 79% (n = 320) maintained glycemic control without insulin. With oral agents, 23.9% of infants (n = 97) were large for gestational age vs 19.9% (n = 79) with insulin (absolute risk difference, 4.0%; 95% CI, −1.7% to 9.8%; P = .09 for noninferiority), with the confidence interval of the risk difference exceeding the absolute noninferiority margin of 8%. Maternal hypoglycemia was reported in 20.9% with oral glucose-lowering agents and 10.9% with insulin (absolute risk difference, 10.0%; 95% CI, 3.7%-21.2%). All other secondary outcomes did not differ between groups.

Conclusions and Relevance

Treatment of gestational diabetes with metformin and additional glyburide, if needed, did not meet criteria for noninferiority compared with insulin with respect to the proportion of infants born large for gestational age.

Trial Registration

Netherlands Trial Registry Identifier: NTR6134