Pregnancy outcomes of gestational diabetes mellitus treated before versus after 24 weeks: A comparison of Carpenter-Coustan and IADPSG criteria.

OBJECTIVE

To compare pregnancy outcomes between early and standard treatment of gestational diabetes mellitus (GDM) diagnosed using the Carpenter-Coustan criteria and to assess the impact of applying the International Association of Diabetes and Pregnancy Study Group (IADPSG) fasting plasma glucose (FPG) threshold.

METHODS

This retrospective cohort study included singleton pregnancies diagnosed with GDM between March 2013 and January 2023. Cases were categorized as early GDM (diagnosed before 24 weeks' gestation) or standard GDM (diagnosed at or after 24 weeks). Maternal and perinatal outcomes were compared, and the impact of substituting an FPG ≥ 92 mg/dL threshold was evaluated.

RESULTS

Of the 1291 cases, 357 were early and 934 were standard GDM. Early treatment did not increase adverse perinatal outcomes compared to standard treatment, except for a modestly longer neonatal hospital stay and a slightly higher neonatal birthweight. The early group had higher rates of chronic hypertension, family history of diabetes, hypertensive disorders of pregnancy (HDP), and higher pre-pregnancy body mass index (BMI, calculated as weight in kilograms divided by the square of height in meters), but insulin treatment rates were similar. In the standard group, FPG ≥ 95 mg/dL was associated with higher neonatal intensive care unit (NICU) admission (18.5% vs. 12.4%, P = 0.03) and neonatal hypoglycemia (4.1% vs. 1.6%, P = 0.04), while FPG ≥ 92 mg/dL did not show significant differences. However, multivariate analysis revealed that FPG ≥ 92 mg/dL was independently associated with NICU admission (adjusted odds ratio [aOR] 1.67; 95% confidence interval [CI], 1.16-2.39). Early GDM, chronic hypertension, and BMI ≥ 25 were significant predictors of HDP.

CONCLUSION

Early treatment using the Carpenter-Coustan criteria did not increase adverse neonatal outcomes. An FPG ≥ 92 mg/dL may identify standard GDM cases at higher risk for neonatal complications.