(VP082) PHARMACEUTICAL TREATMENT OF GESTATIONAL DIABETES MELLITUS AND OBSTETRICAL INTERVENTIONS AND NEONATAL OUTCOMES: A POPULATION-BASED STUDY IN CANADA

Background: Previously, we have shown that mothers with gestational diabetes mellitus (GDM) are at high risk for adverse obstetrical and neonatal outcomes. Evidence on the association between pharmacological treatment of GDM and obstetrical interventions and neonatal outcomes is sparse. Our objective was to compare rates of obstetrical interventions (C-section and labor induction) and neonatal outcomes (large for gestational age [LGA] and neonatal intensive care unit [NICU] use) in pregnancies with and without pharmacologically-treated GDM and no GDM.

METHODS AND RESULTS: We conducted a retrospective population-based cohort study of singleton live births that occurred in Alberta, Canada, between October 1, 2008, and December 31, 2022. We categorized pregnancies as: no-GDM, GDM with pharmacological treatment (GDM-with-Tx), and GDM without pharmacological treatment (GDM-no-Tx).

Of 673,070 live births, 2.3% of pregnancies had GDM-with-Tx (insulin only: 80.8%, insulin + metformin: 6.1%, metformin only: 6.0%), whereas 4.7% had GDM-no-Tx and 92.9% had no-GDM. Metformin use increased from 6.4% (2009 to 20018) to 15.9% (2019 to 2022) over the study period whereas insulin use decreased from 90.0% (2009 to 20018) to 76.0% (2019 to 2022) over the study period. The mothers with GDM had higher obstetrical outcomes compared with those with no GDM (Table 1). The overall C-section rate was higher in the GDM-with-Tx group (42.6%) than in the GDM-no-Tx (36.1%). Similarly, the overall rates of labor induction were higher in the GDM-with-Tx group (57.1%) compared to GDM-no-Tx (43.3%). GDM-with-Tx and GDM-no-Tx pregnancies had worse neonatal outcomes compared with no-GDM controls (Table 1); these included higher rates of LGA (GDM-with-Tx: 14.5%, GDM-no-Tx: 11.6%, no GDM: 8.3%). NICU use was also higher in the GDM than no GDM groups, with no difference between treated and untreated mothers (GDM-with-Tx: 13.1%, GDM-no-Tx: 13.1%, no GDM: 8.8%). There was a decline in LGA rates from 2009 to 2022 in the GDM groups (Figure 1); however, LGA rates were consistently higher in the GDM-with-Tx group compared with the GDM-no-Tx group during the study period.

Conclusion: Mothers with GDM have higher rates of obstetrical interventions regardless of their treatment status, particularly those who received pharmacological treatment. Further research is necessary to understand differences in obstetrical and neonatal outcomes after accounting for their risk profile and type of GDM therapy.