Novel Continuous Glucose Monitoring Metrics and Large-for-Gestational-Age Risk: An Exploratory Retrospective Cohort Study in Pregnancies with Type 1 Diabetes

Background: Continuous glucose monitoring (CGM) improves pregnancy outcomes in patients with type 1 diabetes (T1D). We aimed to assess the between-group differences in glycated hemoglobin (HbA1c) and the incidence of large-for-gestational-age (LGA) neonates in CGM and glucometer users and analyze the potential association of novel CGM metrics with LGA risk in T1D pregnancies. Materials and Methods: Our retrospective study cohort included 134 women with T1D treated with insulin pumps-75 of them used CGM and 59 patients measured their glucose concentrations using glucometers only. As part of our study, we matched the CGM users and patients who preferred the self-monitoring of blood glucose (SMBG) according to their baseline HbA1c and White's diabetes class at a 1:1 ratio. After the matching, both groups included 42 pregnancies. Results: We did not find any difference in changes in HbA1c and perinatal outcomes between CGM and SMBG users; however, we achieved a limited statistical power, and there were more cases of diabetic nephropathy in the SMBG group. Mothers of LGA infants had higher first-trimester HbA1c, time above target, and mean glucose concentrations in each trimester of pregnancy. Other CGM metrics reflecting glucose fluctuations attributed to hyperglycemia were associated with an increased risk of LGA. Despite optimal maternal HbA1c, 39% of neonates demonstrated LGA. Conclusions: Although participants reached the target HbA1c concentrations, mothers of LGA newborns had higher first-trimester HbA1c, as well as higher time above target range, higher mean glucose concentrations, and more glycemic fluctuations, suggesting that several CGM metrics associated with maternal hyperglycemia are associated with LGA in pregnancies with T1D.