More time in range lowers adverse pregnancy outcome risks for patients with diabetes

Key takeaways:

• Time in range increases were tied to lower preeclampsia and large for gestational age risks.
• Normotensive women and those with normal birth weight infants had higher time in range vs. counterparts.

Among pregnant women with type 1 diabetes, more time in optimal glucose range at 12 weeks gestation was associated with lower risks for preeclampsia and large for gestational age infants, researchers reported.

“Given the advantages of time in range over more traditional markers, there has been an increasing focus on evaluating this parameter and its utility as a marker of glycemic control, predictor of outcomes and, ultimately, driver of clinical management in the nonpregnant and pregnant populations,” Nasim C. Sobhani, MD, MAS, assistant professor in the division of maternal-fetal medicine in the department of obstetrics, gynecology and reproductive sciences at the University of California, San Francisco, and colleagues wrote. “In 2019, an international expert consensus suggested a goal time in range of above 70% throughout pregnancy for patients with type 1 diabetes. However, this recommendation was not based on robust data relating specific time in range thresholds to clinically relevant perinatal outcomes.”

Sobhani and colleagues conducted a multicenter retrospective cohort study with data from 91 pregnant women with type 1 diabetes using continuous glucose monitors who delivered from 2020 to 2022 at five University of California Fetal Consortium sites. All women had a continuous glucose monitor target range of 70 mg/dL to 140 mg/dL. Researchers recorded time in range at 12, 16, 20, 24, 28 and 32 weeks.

Primary outcomes were preeclampsia and infants born large for gestational age.

In the cohort, 81% of women used an insulin pump and 72% did not have diabetes-related microvascular disease. Median time since type 1 diabetes diagnosis was 16 years and the median periconception HbA1c was 6.7%. Overall, 29% of women developed preeclampsia.

Normotensive pregnant women had significantly higher time in range, from 56% to 62%, at nearly every time point in gestation compared with women with preeclampsia, with time in range from 43% to 50%.

Twenty-six percent of women had large for gestational age infants. Researchers observed a similar pattern of higher time in range, from 55% to 64%, among women with normal birth weight infants compared with women with large for gestational age infants, with time in range from 41% to 47%.

Every 5-unit time in range increase at 12 weeks gestation was associated with a 45% reduced risk for preeclampsia (adjusted RR = 0.55; 95% CI, 0.3-0.99) and a 46% reduced risk for large for gestational age infants (aRR = 0.54; 95% CI, 0.29-0.99) in adjusted analyses.

“These findings can be used to counsel patients regarding their personal risk of pregnancy complications based on specific time in range and to provide encouragement that even small changes in time in range can improve pregnancy outcomes,” the researchers wrote. “Efforts should be made to replicate these findings in a larger population, to establish evidence-based recommendation for time in range targets in pregnancy, and to explore the association between other continuous glucose monitor parameters and perinatal outcomes.”