Closed-Loop Insulin Pump Effective and Safe in Pregnancy

Insulin delivery with a closed-loop system was at least as effective as continuous subcutaneous insulin infusion in a UK study of pregnant women with type 1 diabetes.…

Lead author Dr. Helen R. Murphy from the University of Cambridge stated that, “At the moment it would be premature to suggest that closed-loop (CL) should supplant conventional CSII (continuous subcutaneous insulin infusion).”

“What we can say,” she added, “is that CL can do just as well as near-optimal CSII and many pregnant women struggle to achieve near optimal CSII day in day out throughout pregnancy. The greatest benefit from CL is likely to be in women with poor glycemic control who otherwise struggle.” “CL is less likely to benefit women with near optimal glucose control,” Dr. Murphy said.

Dr. Murphy and her associates enrolled 12 pregnant women with well-controlled type 1 diabetes in a crossover trial to compare the two insulin delivery methods. Women in the study kept up their normal daily activities and exercise routines and were tested for 24 h on two occasions at 19 and 23 weeks’ gestation.

The primary outcome, plasma glucose time in target, was the same with CL (81%) and CSII (81%), the research team reported. There were more hypoglycemic episodes during CSII (20 episodes, 17 of them symptomatic) than during CL (13 episodes, eight of them symptomatic). The percentage of time hypoglycemic to 45 mg/dL or lower was significantly higher with CSII than with CL, and the low blood glucose index (a measure of the duration and extent of hypoglycemia) was significantly better with CL than with CSII.

Overnight plasma glucose time in target was very high with both methods: 100% with CL and 95% with CSII.

“The achievement of 100% overnight time in target provides support for further investigation of closed-loop systems in pregnancy,” the investigators conclude.

“Now that we have tested the CL system our next step is to perform longer duration studies, in the home setting,” Dr. Murphy said. “The women in this current study were very well controlled during the 24-hr hospital visit but continuous glucose monitoring data from the days before and after their hospital visit suggested that they were unable to maintain such tight blood glucose control at home.”

Diabetes Care online Oct. 19, 2011