Objective: We aim to identify obstetric outcomes for pregnancies with gestational diabetes (GDM) treated with oral agents only, insulin only, and failed oral agents. Methods: This is a retrospective cohort study of 617 patients with GDM at a single academic center, 2011-2018. We excluded patients with pre-GDM and GDM managed by diet. We stratified by treatment: oral agents only (referent), failed oral agents (transitioned to insulin), and insulin only and compared outcomes between groups. Generalized linear modeling was used to account for group difference and biologically plausible covariates. Results: Most patients took oral agents only (74.5%), 7.1% failed oral agents, and 19.7% were treated with insulin only. Patients on oral agents only were more likely to be non-White race (37.9% oral only, 51.4% failure, 44.6% insulin only, p90. Insulin-only treatment was associated with decreased risk of EFW90, perhaps indicating that identifying patients likely to fail oral agents could improve outcomes.