Maternal and neonatal outcomes in gestational diabetes mellitus: a retrospective cohort study stratified by fasting hyperglycemia phenotype.

BACKGROUND AND AIM: Gestational diabetes mellitus (GDM) encompasses distinct metabolic phenotypes. While post-load glucose spikes reflect peripheral insulin resistance, impaired fasting glucose (IFG) reflects hepatic insulin resistance. This study aims to characterize GDM phenotypes stratified by baseline fasting glucose status and evaluate their maternal and neonatal outcomes within a standardized management pathway. METHODS AND RESULTS: This retrospective cohort study analyzed 1216 women with singleton pregnancies diagnosed with GDM using IADPSG criteria (2014-2022). Patients were stratified into Group 1 (IFG, fasting glucose ≥92 mg/dL, n = 741) and Group 2 (Normal Fasting Glucose [NFG], n = 475). All patients received standardized care including medical nutrition therapy and insulin when required. The IFG group had a significantly higher prevalence of pre-gestational obesity (30.4% vs 12.2%, p < 0.0001) and required insulin therapy four times more frequently (32.2% vs 8.8%, p < 0.0001). After multivariable adjustment, the IFG phenotype remained a robust independent predictor for large-for-gestational-age (LGA) infants (adjusted OR 1.82, 95% CI 1.21-2.74, p = 0.004) and labor induction (adjusted OR 1.44, 95% CI 1.11-1.86, p = 0.0016). No statistically significant differences were observed between groups regarding acute neonatal complications, including hypoglycemia (5.9% vs 6.1%, p = 0.88) and respiratory distress (8.6% vs 6.9%, p = 0.28). CONCLUSIONS: Fasting hyperglycemia identifies a high-risk GDM phenotype characterized by elevated baseline metabolic risks, higher insulin requirements, and increased rates of obstetric interventions and LGA infants. Within a standardized management setting, acute neonatal metabolic complications did not differ between groups. Baseline fasting glucose serves as an effective stratification tool to target intensive prenatal surveillance.