Abstract
Pregnancy complicated by type 1 diabetes mellitus is associated with increased maternal and fetal morbidity and mortality. 1 Tight glycemic control correlates with improved outcomes.2-4 The CONCEPTT trial using the Medtronic Guardian, found continuous glucose monitoring (CGM) is associated with fewer fetal adverse outcomes. 2 Dexcom G6 has been found to have an overall mean absolute relative difference (MARD) of 10.3% and a MARD of 8.7% when worn on the posterior upper arm in pregnant women. 5 In the United States, CGM use during pregnancy has risen over the past several years, 6 but is not yet Food and Drug Administration (FDA) approved for use in pregnancy. Data on clinical experience and pregnancy outcomes are limited.
We present retrospective data from 50 pregnancies in 42 women (51 infants) who received prenatal care at 3 U.S. sites from 2/2012 to 7/2019 and used a Dexcom G4, G5, or G6 CGM (Table 1). Data were retrieved from medical records and CGM reports, which were downloaded as part of routine care and reviewed. The study was approved by each institution’s local IRB.
Subject Demographics, CGM Use, and Maternal and Fetal Outcomes.
Available N given for each metric from total possible of 42 women, 50 pregnancies (49 singleton, 1 twin), 51 infants. Mean ± standard deviation or mean (interquartile range: IQR) for quantitative data as indicated and count (percent) for categorical data.
Large for gestational age (LGA) was defined as birth weight greater than 90th percentile for gestational age.
Small for gestational age (SGA) was defined as birth weight less than 10th percentile for gestational age.
Mean HbA1c during pregnancy was 6.1 ± 0.69%. CGM was used for the entire pregnancy in 84% of pregnancies. Four subjects (8%) started CGM during their second or third trimesters, respectively. No women stopped CGM use during pregnancy. The number of fingerstick tests recommended by providers and/or performed by patients varied widely, with some women relying on CGM values almost exclusively for treatment decisions and others using them adjunctively. Women wore sensors on the front and back abdomen, arms, buttocks, and thighs in all stages of pregnancy, labor and delivery, and postpartum period based on personal preference. The median wear time based on CGM download reports was 93% (IQR: 81-98%). No skin-related adverse events, such as infection or severe irritation, were reported. Eight women (16%) reported perceived inaccuracies during CGM use compared to fingerstick glucose values during pregnancy. The most commonly documented reason for decreased sensor wear time was insurance coverage restrictions.
No women reported severe hypoglycemia or diabetic ketoacidosis while wearing CGM. One woman had recurrent severe hypoglycemia requiring emergency care prior to starting CGM, but none after starting Dexcom G5 CGM. Six women (12%) were diagnosed with pre-eclampsia. Four (8%) and 7 (14%) infants were born at less than 34 and 37 weeks, respectively. Cesarean section was performed in 29 (60%) subjects. Median birth weight was 3530 g (IQR: 3160-3721): 12 infants (27%) and 2 infants (4%) were large and small for gestational age, respectively. One fetus had intrauterine growth restriction (born at 28 weeks), and one infant had neonatal respiratory distress syndrome (born at 34 weeks). There were no cases of still births or perinatal mortality.
Self-monitoring of blood glucose, the standard of care, can result in missed hyper- and hypoglycemic episodes and does not provide complete information about trends in recent glucose levels. Our data support the prevailing belief among care providers that CGM is a useful and well-tolerated tool for management of diabetes during pregnancy.
Footnotes
Acknowledgements
The authors would like to acknowledge the contributions of Selassie Ogyaadu, MD, Sally Xie, MD, Molly Piper, and Georgia Kulina, MD for their study coordination, chart review, and data management.
Abbreviations
CGM, continuous glucose monitoring; IQR, interquartile range; LGA, large for gestational age; MARD, mean absolute relative difference; SGA, small for gestational age; US, United States.
Declaration of Conflicting Interests
The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: GO receives research support from Tandem Diabetes, Dexcom, and Abbott paid to her institution. BR has no disclosures to report. EVN has no disclosures to report. YCK receives consulting fees from Novo Nordisk and product support from Dexcom, Roche Diabetes, and Tandem Diabetes. SSS has no disclosures to report. CL receives research support from Tandem Diabetes, Dexcom, and Abbott paid to her institution. RK has no disclosures to report. JEP is currently an employee of Tandem Diabetes Care, Inc. The work presented in the manuscript was performed as part of his academic appointment at Sansum Diabetes Research Institute and is independent of his employment with Tandem Diabetes Care. KC receives research support from Dexcom, Medtronic, Abbott, Insulet, and Novo Nordisk paid to her institution. MMC has no disclosures to report. ED reports receiving grants from JDRF, NIH, and Helmsley Charitable Trust, personal fees from Roche, Dexcom and Eli Lilly, patents on artificial pancreas technology, and product support from Dexcom, Insulet, Tandem, and Roche. ED is currently an employee and shareholder of Eli Lilly and Company. The work presented in this manuscript was performed as part of his academic appointment and is independent of his employment with Eli Lilly and Company. CJL receives research support from Tandem Diabetes, Dexcom, and Abbott paid to her institution and has served as a consultant and CME speaker for Dexcom and as a consultant for Eli Lilly.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
