Hybrid closed-loop therapy significantly improved maternal glucose control during pregnancy complicated by type 1 diabetes

Achieving tight glucose control during pregnancy is important in order to reduce maternal and neonatal complications such as premature labour, large birthweight and neonatal hypoglycaemia. As such, target glucose level is often set to be more stringent when compared with non-pregnant levels. Glycaemic control, however, is often more challenging during pregnancy due to unpredictable eating patterns, reduced physical activity and secretions of placental hormones linked to insulin resistance. For many patients, the use of standard multiple insulin injections a day and/or insulin pump therapy is still quite onerous due to the need to make insulin adjustments often more than five times a day. A closed-loop system, however, automatically adjusts insulin levels according to blood glucose levels every 10 min, but their efficacy during pregnancy remains unclear.

A new study, published in the New England Journal of Medicine,¹ has found that pregnant women using hybrid closed-loop system spend 2.5 more hours per days in the target blood sugar range compared with standard therapy, with no unexpected safety issues being reported. This randomized controlled trial included 124 pregnant women with type 1 diabetes from nine hospitals in England, Scotland and Northern Ireland. The mean age was 31 years, and 93% of the participants were White. Before 16 weeks' gestation, participants were randomized to a standard insulin pump (N = 63) and a closed-loop system (N = 61) with both groups having continuous glucose monitoring on their phone.

The study found that those on the closed-loop group spent 12% more time within the target blood sugar range for pregnant women (3.5–7.8 mmol/L) than the participants in the standard pump group (68% vs. 56%). Additionally, the pregnant women in the closed-loop group spent less time above range (29%) than those in the standard pump group (41%), had more overnight time in the target range (difference, 12.3%) and had lower HbA1c level (difference, −0.31%). Little time was spent in a hypoglycemic state. Interestingly, women who used the closed-loop system gained 3.7 kg less weight during pregnancy.

In my opinion, this is a landmark study on the best strategy to optimize glycaemic control in pregnancy. This study provides clear and compelling benefits of using hybrid closed-loop technology during pregnancy for people with type 1 diabetes. As such, the UK National Institute of Health and Care Excellence has now recommended closed loop as an option for all women with type 1 diabetes who are pregnant or planning pregnancy.