Continuous glucose monitoring in pregnancies with type 1 diabetes: small increases in time-in-range improve maternal and perinatal outcomes

• Published in: American journal of obstetrics and gynecology 2024-10, Vol.231 (4), p.467.e1-467.e8
• Main Authors: Sobhani, Nasim C., Goemans, Sophie, Nguyen, Antoinette, Chambers, Melissa E., Richley, Michael, Gabby, Lauryn C., Field, Nancy, Han, Christina S., Ramos, Gladys A.
• Format: Article
• Language: English
• Subjects: diabetes in pregnancy; diabetes technology; glycemic control; hyperglycemia in pregnancy
• ISSN: 0002-9378; 1097-6868; 1097-6868
• DOI: 10.1016/j.ajog.2024.01.010

Continuous glucose monitors provide detailed information regarding glycemic control in pregnant patients with type 1 diabetes. Little data have been published examining the association between continuous glucose monitor parameters and perinatal outcomes among gravidas with type 1 diabetes using continuous glucose monitors. This study aimed to examine the association between perinatal outcomes and time-in-range as assessed by continuous glucose monitors used in pregnant individuals with type 1 diabetes. We hypothesized that higher time-in-range would be associated with lower risk of adverse perinatal outcomes. This multicenter retrospective cohort study included all gravidas with type 1 diabetes using continuous glucose monitors who delivered from 2020 to 2022 at 5 University of California sites. Only those with continuous glucose monitor target range set to 70 to 140 mg/dL (±10 mg/dL) were included. Time-in-range (%) was recorded at 12, 16, 20, 24, 28, and 32 weeks. The primary maternal and neonatal outcomes were preeclampsia and large for gestational age, defined as birthweight ≥95th percentile. Kruskal–Wallis tests were used to compare median time-in-range between those with and without the primary outcomes. Log-binomial regression was used to obtain risk ratios, with adjustment for microvascular disease and years with type 1 diabetes. A total of 91 patients were included. Most used an insulin pump (81%) and did not have diabetic microvascular disease (72%). Median time since diagnosis of type 1 diabetes was 16 years, and median periconception hemoglobin A1c was 6.7%. Compared with those with preeclampsia, normotensive gravidas had significantly higher time-in-range at nearly every time point. A similar pattern was observed for those with normal-birthweight infants compared with large-for-gestational-age infants. On adjusted analyses, every 5-unit increase in time-in-range at 12 weeks was associated with 45% and 46% reductions in the risks of preeclampsia and large for gestational age, respectively (preeclampsia: adjusted risk ratio, 0.55; 95% confidence interval, 0.30–0.99; large for gestational age: adjusted risk ratio, 0.54; 95% confidence interval, 0.29–0.99). Higher time-in-range is associated with lower risk of preeclampsia and large for gestational age. This association is observed early in gestation, when each 5-unit increase in time-in-range is associated with ∼50% reduction in the risk of these complications. These findings can be used to couns