Written by Peter Liu
Spoon Feed
Starting metformin +/- glyburide before insulin in patients with gestational diabetes was not noninferior to upfront insulin for preventing large-for-gestational-age (LGA) infants and had more maternal hypoglycemia.
Oral agents don’t beat plain old insulin for GDM
Gestational diabetes mellitus (GDM) occurs in 8% of births in the US, resulting in several risks to mother and offspring, including macrosomia and LGA. GDM patients without adequate glycemic control from lifestyle modification benefit from initiation of insulin or an oral antihyperglycemic medication such as metformin or glyburide. Though metformin has decreased risk of macrosomia, glyburide use probably causes macrosomia and greater neonatal hypoglycemia. Ultimately, insulin is frequently the go-to treatment, with better reliability and definitive glycemic control if patients adhere. This randomized, open-label noninferiority trial examined whether a sequential oral glucose-lowering strategy, using metformin first and then glyburide if needed, was noninferior to insulin in preventing LGA infants among 820 pregnant women with gestational diabetes across 25 Dutch centers. The primary outcome – LGA incidence – was 23.9% in the oral agents group versus 19.9% in the insulin group (absolute risk difference 4.0%, 95%CI -1.7% to 9.8%), failing to meet the 8% noninferiority margin. Maternal hypoglycemia was more frequent with oral agents (20.9% vs. 10.9%).
How does this change my practice?
While I rarely manage GDM upfront as a hospitalist, this study highlights the main considerations in pharmacotherapy for GDM. In particular, it reiterates clear downsides to glyburide therapy for GDM seen in other meta-analyses and makes me strongly disfavor its use, either as an adjunct with concomitant metformin or as an alternative to metformin or insulin monotherapy.
Source
Oral Glucose-Lowering Agents vs Insulin for Gestational Diabetes: A Randomized Clinical Trial. JAMA. 2025 Jan 6. doi: 10.1001/jama.2024.23410. Epub ahead of print. PMID: 39761054
