Intrapartum continuous glucose monitor metrics and neonatal hypoglycemia.

OBJECTIVE:: Birthing individuals with pregestational diabetes (Type 1 [T1DM] or Type 2 ]T2DM]) are routinely using continuous glucose monitors (CGMs), and their offspring are at risk for hypoglycemia. The International Consensus of Use of Continuous Glucose Monitoring recommends a time in range target of greater than 70% in pregnancy but also notes that specific data in patients with T2DM are lacking and do not make specific recommendations regarding intrapartum CGM use or intrapartum glycemic targets., Therefore, the objective of this study was to characterize intrapartum glycemic metrics via CGMs among patients with pregestational diabetes and assess its relationship with neonatal hypoglycemia.

STUDY DESIGN:: We conducted a retrospective cohort study of all obstetric patients with a diagnosis of T1DM or T2DM and intrapartum CGM use with a Dexcom device at a single large academic tertiary care center from July 1, 2022, to June 1, 2024. All patients were managed in accordance with a standard intrapartum glycemic protocol, with patients with T1DM receiving either IV insulin infusion or continuation of an insulin pump intrapartum. The study was approved by the UMass Chan School of Medicine Institutional Review Board (STUDY00001769). All pregnancy patients had glycemic target ranges set to 63 to 140 mg/dL. Initial maternal glucose measurements obtained via CGM were validated against fingerstick glucose measurements to ensure values were within 20%. The main outcome of interest was neonatal glucose, which was measured according to a standard hospital protocol for all patients with pregestational diabetes. Neonatal glucose was characterized by the mean first neonatal glucose level obtained within 1 hour of birth, the mean neonatal glucose 24 hours after birth, and if the neonate required treatment (both oral and/or intravenous) for hypoglycemia. Demographic and clinical outcomes were summarized as means and standard deviations for continuous variables and percentages for categorical variables. Pearson correlation coefficient was performed between glycemic metrics and neonatal hypoglycemia.

RESULTS:: During the study period, 43 patients were found to be eligible for inclusion. Birthing individuals were 31.0 years old, predominately White (65.1%), and non-Hispanic (76.7%). Approximately 62.8% of patients had T1DM and 37.2% had T2DM (Table 1). The mean first neonatal glucose after birth was 50.6 mg/dL, and the mean neonatal glucose 24 hours after birth was 64.0 mg/dL. Nearly two-thirds (62.8%) of neonates were treated for hypoglycemia (Table 2). When assessing first neonatal glucose, there were weak to no associations between all glycemic metrics, including time above range (r=0.03), time in range (r=0.02), and time below range (r=−0.14). When assessing neonatal glucose 24 hours after birth, there were again weak associations between time above range (r=−0.34) and time below range (r=−0.29). There was a moderate positive correlation between time in range and neonatal glucose 24 hours after birth (r=0.49).

CONCLUSION:: The study found that while CGM can be used to obtain glycemic information intrapartum, glycemic metrics do not seem to correlate well with neonatal glucose levels both immediately and 24 hours after birth. Our study found similar findings to the study completed by Bartal and colleagues. They performed a prospective study of patients with both gestational and pregestational diabetes and applied CGMs during the intrapartum period. They found that overall CGM metrics were a poor predictor of neonatal hypoglycemia, but that time above range was associated with higher rates of neonatal hypoglycemia. One key difference between this study and the current literature is the difference in intrapartum glycemic targets utilized. This difference may explain the variation in findings, but overall, it appears that CGM metrics, and perhaps even intrapartum glycemic control overall, are poor predictors for neonatal hypoglycemia. Given the lack of agreement on an intrapartum target, we chose to use the pregnancy range (63–140 mg/dL), but future studies should examine different intrapartum targets via CGM metrics. Society guidelines should reach a standardized definition of glycemic targets in pregnancy to allow for improved research and clinical guidance. This study is limited by its small sample size and combination of patients with T1DM and T2DM. Due to the small sample size, adjusted analyses for confounders and stratified analysis by type of pregestational diabetes were not feasible. In conclusion, this study showed that intrapartum glycemic metrics by CGM metrics are overall weakly associated with neonatal hypoglycemia.