Continuous Glucose Monitoring–Derived Differences in Pregnancies With and Without Adverse Perinatal Outcomes

OBJECTIVE: To evaluate whether continuous glucose monitoring (CGM)–derived glycemic patterns observed throughout pregnancy were associated with adverse perinatal outcomes, specifically fetal growth disorders and hypertensive disorders of pregnancy (HDP). METHODS: We conducted a prospective observational study of individuals with viable singleton pregnancies and screening hemoglobin A 1c levels less than 6.5%. Those with preexisting diabetes were excluded. Enrollment occurred at the earliest gestational age before 17 weeks. Participants wore blinded continuous glucose monitors consecutively as willing until delivery. Those with at least 14 days of CGM data were included in analysis. Rates of large-for-gestational-age (LGA) neonates, small-for-gestational age (SGA) neonates, and HDP were assessed. Continuous glucose monitoring–derived glycemic metrics were calculated, including mean glucose level and percent time above and below thresholds. Two-sample t tests were used to compare glycemic metrics between participants with and without adverse perinatal outcomes. RESULTS: Of 937 participants enrolled, 760 met inclusion criteria. Those delivering LGA neonates or who were diagnosed with HDP had higher mean glucose levels (102±9 vs 100±8, P =.01 and 103±8 vs 99±8, P <.001) and spent more time above 120 mg/dL (median 16% vs 12%, P =.006, and 16% vs 12%, P <.001, respectively) and above 140 mg/dL (median 3.9% vs 2.8%, P =.006, and 3.5% vs 2.8%, P <.001, respectively) throughout gestation than those without these outcomes. These findings were present regardless of gestational diabetes mellitus status. Participants with SGA neonates had lower mean glucose levels (97±7 vs 101±8, P =.01) and spent less time above 140 mg/dL (median 1.6% vs 2.3%, P =.01) and more time below 63 mg/dL (median 3.0% vs 2.3%, P =.02) than those without SGA neonates. CONCLUSION: Individuals with LGA neonates or HDP exhibit a slightly higher mean glucose levels and spend more time hyperglycemic in early pregnancy than those who do not experience these outcomes.