The closed-loop insulin system during pregnancy

This study examined whether closed-loop or “automated” delivery of insulin would be a suitable treatment for pregnant women with type-1 diabetes. The authors concluded that the closed-loop therapy successfully controlled blood-sugar levels during pregnancy, labor and delivery.

Type-1 diabetes (T1D) occurs when the body cannot absorb sugar properly due to a lack of the hormone “insulin”. Keeping blood-sugar levels within recommended ranges is the best way to avoid potential complications (for mother and baby) during pregnancy. This must be balanced, however, with avoiding the risk of hypoglycemia (too low blood sugar). 

Insulin requirements increase during pregnancy for women with T1D. The dose of insulin therefore needs to be adjusted regularly. Closed-loop insulin delivery is one methods that could potentially be used during pregnancy. With this automated therapy, a computer uses a set of mathematical instructions to adjust insulin-pump delivery in response to changing blood-sugar levels. It is not clear whether this is more effective at controlling blood glucose levels compared to an insulin pump or injections.

This study included 16 pregnant women with T1D. These patients were between 8 and 24 weeks' pregnant and were already receiving insulin therapy via injections or an insulin pump. They women had an HbA1c (average blood glucose over 3 months) between 6.5% and 10.0%.  All patients used the closed-loop system for four weeks and an insulin pump for four weeks at night. Patients were randomly assigned to which was used first. Patients then had the choice of using either system day and night for an average of 14.6 weeks. Fourteen women went through labor and birth during this period.

Overnight blood glucose levels remained in the target range 74.7% of the time for patients using the closed loop system. In comparison, levels were in the target range 59.5% of the time with the insulin pump. Average blood glucose levels were an average of 0.8 mmol/L lower with the closed loop system.

During the 14.6 week continuation period, patients using the closed loop system reached target blood glucose levels 68.7% of the time. No episodes of severe hypoglycemia were reported in either group.

This study concluded that closed-loop insulin delivery was better at controlling blood-glucose levels than the insulin pump in pregnant women with T1D.

Larger and longer-duration trials are needed to confirm these results.

Discuss insulin deliver options and methods of controlling blood glucose levels with your doctor.