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

Nasim C Sobhani; Sophie Goemans; Antoinette Nguyen; Melissa E Chambers; Michael Richley; Lauryn C Gabby; Nancy Field; Christina S Han; Gladys A Ramos

doi:10.1016/j.ajog.2024.01.010

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

Am J Obstet Gynecol. 2024 Jan 17:S0002-9378(24)00024-3. doi: 10.1016/j.ajog.2024.01.010. Online ahead of print.

Authors

Nasim C Sobhani¹, Sophie Goemans², Antoinette Nguyen³, Melissa E Chambers⁴, Michael Richley⁵, Lauryn C Gabby², Nancy Field⁶, Christina S Han⁵, Gladys A Ramos²

Affiliations

¹ Division of Maternal Fetal Medicine, Department of Obstetrics, Gynecology & Reproductive Sciences, University of California San Francisco, San Francisco, CA. Electronic address: Nasim.Sobhani@UCSF.edu.
² Division of Maternal Fetal Medicine, Department of Obstetrics, Gynecology & Reproductive Sciences, University of California San Diego, San Diego, CA.
³ School of Medicine & Dentistry, University of Rochester, Rochester, NY.
⁴ Division of Maternal Fetal Medicine, Department of Obstetrics & Gynecology, University of California Irvine, Irvine, CA.
⁵ Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, University of California Los Angeles, Los Angeles, CA.
⁶ Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, University of California Davis, Davis, CA.

PMID: 38242337
DOI: 10.1016/j.ajog.2024.01.010

Abstract

Background: 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.

Objective: 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.

Study design: 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.

Results: 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).

Conclusion: 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 counsel patients regarding the risk of pregnancy complications at specific time-in-range values, and to encourage patients that even small improvements in time-in-range can have significant impact on pregnancy outcomes. Larger studies are needed to further explore these findings and to identify optimal time-in-range to reduce perinatal complication rates.

Keywords: diabetes in pregnancy; diabetes technology; glycemic control; hyperglycemia in pregnancy.