Association between glycemic variability and composite adverse neonatal outcomes in patients with gestational diabetes mellitus: a retrospective study

Objective Glycemic variability (GV) has emerged as a potential contributor to adverse pregnancy outcomes beyond mean glucose levels. This study aimed to investigate the association between GV indices derived from self-monitoring of blood glucose (SMBG) and composite adverse neonatal outcomes (CANO) in patients with gestational diabetes mellitus (GDM).Methods This retrospective study included 160 women with GDM who delivered at Guiyang Maternal and Child Health Hospital between January 2022 and December 2024. GV indices, including standard deviation (SD), coefficient of variation (CV), and mean amplitude of glycemic excursions (MAGE), were calculated from SMBG data. CANO was defined as the occurrence of at least one of: macrosomia, large for gestational age, small for gestational age, neonatal hypoglycemia, jaundice requiring phototherapy, respiratory distress syndrome, NICU admission >24 h, or preterm birth. Multivariable logistic regression was used to evaluate the association between GV indices and CANO, adjusting for maternal characteristics and glycemic control parameters.Results CANO occurred in 67 patients (41.88%). The CANO group had higher glucose SD (1.38 ± 0.32 vs. 1.18 ± 0.31 mmol/L [24.8 ± 5.8 vs. 21.2 ± 5.6 mg/dL]), CV (21.63 ± 5.32% vs. 19.19 ± 5.25%), and MAGE (2.86 ± 0.72 vs. 2.52 ± 0.65 mmol/L [51.5 ± 13.0 vs. 45.4 ± 11.7 mg/dL]) compared with those without CANO. After adjustment for confounders, glucose SD (OR = 1.85 per 0.5 mmol/L [9.0 mg/dL], 95% CI: 1.18–2.90, p = 0.007) and CV (OR = 1.48 per 5%, 95% CI: 1.12–1.96, p = 0.006) remained independently associated with CANO, whereas MAGE did not retain significance (OR = 1.42, 95% CI: 0.92–2.19, p = 0.112). These associations remained robust after excluding SGA from the composite endpoint and across all other sensitivity analyses. Receiver operating characteristic analysis showed modest predictive performance, with glucose SD having the highest AUC of 0.652.Conclusion Glycemic variability, measured by glucose SD and CV from SMBG data, was independently associated with CANO in women with GDM, though with limited discriminative ability as a standalone predictor. Future prospective studies with larger sample sizes and CGM-derived metrics are needed to validate these findings.