Continuous Glucose Monitoring Metrics and Perinatal Outcomes in Pregnant Women with Type 2 Diabetes

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.

To examine associations between continuous glucose monitoring (CGM)-derived metrics and perinatal outcomes throughout pregnancy and across gestational windows in women with T2D.

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.

Among 80 women (mean (±standard deviation) age 34 ± 6 years; body mass index 33 ± 7 kg/m²; 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.

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.