Diabetes and Pregnancy

Diabetes itself is a risk factor in pregnancy, complicating up to 10% in the United States. Of these, 0.2% to 0.5% are patients with type 1 diabetes mellitus (T1DM). Reports suggest pregnancies affected by T1DM are at increased risk for preterm delivery, preeclampsia, macrosomia, shoulder dystocia, intrauterine fetal demise, fetal growth restriction, cardiac and renal malformations, in addition to rare neural conditions such as sacral agenesis.

Few studies report hybrid closed-loop insulin therapy has shown promise for management of type 1 diabetes during pregnancy; however, its efficacy is unclear. A new study in New England Journal of Medicine aimed to evaluate the same, and found that hybrid closed-loop therapy significantly improved maternal glycemic control during pregnancy complicated by type 1 diabetes.

Researchers conducted a multicenter, controlled trial, we randomly assigned pregnant women with type 1 diabetes and a glycated hemoglobin level of at least 6.5% at nine sites in the United Kingdom to receive standard insulin therapy or hybrid closed-loop therapy, with both groups using continuous glucose monitoring. The primary outcome was the percentage of time in the pregnancy-specific target glucose range (63 to 140 mg per deciliter [3.5 to 7.8 mmol per liter]) as measured by continuous glucose monitoring from 16 weeks’ gestation until delivery. Analyses were performed according to the intention-to-treat principle. Key secondary outcomes were the percentage of time spent in a hyperglycemic state (glucose level >140 mg per deciliter), overnight time in the target range, the glycated hemoglobin level, and safety events.

Key Findings of the Study

• A total of 124 participants with a mean (±SD) age of 31.1±5.3 years and a mean baseline glycated hemoglobin level of 7.7±1.2% underwent randomization.
• The mean percentage of time that the maternal glucose level was in the target range was 68.2±10.5% in the closed-loop group and 55.6±12.5% in the standard-care group.
• Results for the secondary outcomes were consistent with those of the primary outcome; participants in the closed-loop group spent less time in a hyperglycemic state than those in the standard-care group; had more overnight time in the target range, and had lower glycated hemoglobin levels.
• Little time was spent in a hypoglycemic state. No unanticipated safety problems associated with the use of closed-loop therapy during pregnancy occurred (6 instances of severe hypoglycemia, vs. 5 in the standard-care group; 1 instance of diabetic ketoacidosis in each group; and 12 device-related adverse events in the closed-loop group, 7 related to closed-loop therapy).

Researchers concluded that “Hybrid closed-loop therapy significantly improved maternal glycemic control during pregnancy complicated by type 1 diabetes.”

Reference: Tara T.M. Lee, M.B., B.S., Corinne Collett, B.Sc., Simon Bergford, M.S.; Automated Insulin Delivery in Women with Pregnancy Complicated by Type 1 Diabetes, N Engl J Med 2023; 389:1566-1578; DOI: 10.1056/NEJMoa2303911.