Association of childhood‐ versus adult‐onset type 1 diabetes in pregnancy with maternal, neonatal, and glycemic control outcomes

Abstract Introduction Type 1 diabetes mellitus (T1DM) is associated with heightened risk of adverse pregnancy outcomes. Genetic, immune, cardiometabolic, and psychosocial differences exist between childhood‐ and adult‐onset T1DM, yet how these differences may influence pregnancy outcomes remains poorly understood. Differences in pregnancy and glycemic outcomes by duration of diabetes have not been evaluated in the context of diabetes technology in pregnancy. Methods This single‐center retrospective cohort study (2018–2023) compared pregnant people using a Dexcom G6 continuous glucose monitor with T1DM diagnosed in childhood (<18 years of age) with those diagnosed in adulthood (≥18 years of age). Co‐primary outcomes were hypertensive disorders of pregnancy and neonatal hypoglycemia. Secondary outcomes were estimated blood loss, cesarean birth, gestational weight gain, gestational age at birth, preterm birth, neonatal intensive care unit (NICU) admission and length of stay, birthweight, large‐for‐gestational age neonate, respiratory distress syndrome, hyperbilirubinemia, and 5‐min Apgar scores. Glycemic metrics by trimester included time‐in/above/below‐range, coefficient of variation, mean glucose, and hemoglobin A1c. Multivariable logistic regression and generalized linear models estimated adjusted odds ratios (aORs) or adjusted mean differences (aMDs) and 95% confidence intervals (CIs), adjusted for body mass index. Results Of 102 individuals in the cohort, 61 (60%) had childhood‐onset T1DM. Median duration since diagnosis was 22 years (interquartile range [IQR], 18–27) in the childhood‐onset group and 6 years (IQR, 3, 11.5) in the adult‐onset group. Odds of hypertensive disorders of pregnancy (39% vs. 27%; aOR, 1.5; 95% CI, 0.6–3.7) did not differ between childhood‐ and adult‐onset T1DM. The childhood‐onset group demonstrated higher point estimates for frequency of neonatal hypoglycemia (47% vs. 27%; aOR, 2.4; 95% CI, 1.0–5.8), higher incidence of preterm birth (25% vs. 10%; aOR, 3.5; 95% CI, 1.02–11.8), and neonates with longer median duration of NICU admission (13.5 vs. 4 days; aMD, 10.1; 95% CI, 1.1–19.2). Continuous glucose monitoring metrics were similar between groups, except for lower first‐trimester time in range in the childhood‐onset group (57.5% vs. 65.3%; aMD, −7.4; 95% CI, −0.6 to −14.1). Conclusion Childhood‐onset T1DM is not associated with hypertensive disorders of pregnancy, but does appear linked to higher risk of neonatal hypoglycemia, preterm birth, and longer length of NICU stay, which can inform counseling in this at‐risk population.