Continuous glucose monitoring parameters in pregnancy-related complications in patients with type 1 diabetes: a retrospective cohort study

Continuous glucose monitoring (CGM) improves pregnancy outcomes in patients with type 1 diabetes (T1D). The primary study objective was to analyze associations between numerous novel CGM parameters and neonatal complications, such as large‑for‑gestational‑age (LGA) neonates, hypoglycemia, hyperbilirubinemia, transient breathing disorders, preterm births, as well as pre‑eclampsia. In this single‑center retrospective cohort study, we recruited 102 eligible pregnant women with T1D who were treated with sensor‑augmented pumps with suspend‑before‑low function from the first trimester. The pregnant patients were admitted for at least 1 control hospital visit in each trimester of gestation for anthropometric and laboratory measurements and collection of sensor data. The median (interquartile range) percentage values for glycated hemoglobin (HbA1c) (first trimester, 6.23 [5.91-6.9]; second trimester, 5.49 [5.16-5.9]; third trimester, 5.75 [5.39-6.29]) and for time‑in‑range (first trimester, 72.4 [67.3-80.3]; second trimester, 72.5 [64.7-79.6]; third trimester, 75.9 [67.1-81.4] met the criteria of well‑controlled T1D in each trimester of pregnancy. Nonetheless, we noted 27% of LGA births, 25% of neonatal hypoglycemia, 33% of hyperbilirubinemia, and 13% of preterm births. Worse glycemic control and more glycemic fluctuations in the second and third trimesters were mainly associated with increased risk of LGA at birth, transient breathing disorders, and hyperbilirubinemia. CGM parameters (mean of daily differences, high blood glucose index, glycemic risk assessment in diabetes equation, or continuous overall net glycemic action) in the patients with T1D are significantly associated with the increased risk of LGA at birth and neonatal transient breathing disorders and hyperbilirubinemia. However, we did not find evidence that novel CGM indices could be more effective in predicting those events than the commonly used CGM parameters or HbA1c levels.