Background: The rising incidence of early-onset type 2 diabetes (T2D) has made it the leading cause of pregestational diabetes worldwide. However, real-world data on glycemic control during pregnancy and its association with perinatal outcomes remain limited. Objective: To examine associations between continuous glucose monitoring (CGM)-derived metrics and perinatal outcomes throughout pregnancy and across gestational windows in women with T2D. Methods: We conducted a single-center retrospective cohort study including all pregnant women with T2D who delivered between January 2020 and August 2025 and used CGM for ≥7 days ( n = 80). The primary composite outcome included preterm birth (<37 weeks), large-for-gestational-age infant, neonatal hypoglycemia, shoulder dystocia, neonatal intensive care admission, hyperbilirubinemia, or perinatal mortality. CGM metrics included mean glucose, time in range (TIR 63–140 ), time below range, and glucose coefficient of variation. Associations were assessed using mean differences and adjusted logistic regression. Results: Among 80 women (mean (±standard deviation) age 34 ± 6 years; body mass index 33 ± 7 kg/m 2 ; glycated hemoglobin 7.4% ± 1.7%), 24 (30%) were diagnosed during pregnancy. Median (interquartile range) CGM use was 118 (69–187) days. Mean TIR 63–140 was 72% ± 13%; 50 (63%) women achieved TIR 63–140 ≥70%, 19 (24%) achieved ≥80%, and only 5 (6%) achieved the ≥90% target. Perinatal events occurred in 53 (66%) women. Mean glucose was higher (+11 mg/dL; 95% confidence interval CI, +5 to +16) and TIR lower (–8.1 percentage points; 95% CI, –13.2 to –3.0) in women with events, with differences apparent from 9 to 12 weeks of gestation. Each 10-point decrease in TIR 63–140 was associated with higher odds of perinatal events (adjusted odds ratio 1.82; 95% CI, 1.19–3.00). No significant differences were observed for other CGM-derived metrics. Conclusion: In women with T2D, poorer CGM-assessed glycemic control was associated with perinatal events from early pregnancy. Few women achieved the recommended glycemic targets, highlighting the need for improved management and prevention.
Chemoul et al. (2026) studied this question.