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06-02-2023 | Type 1 diabetes | News

Pregnancy-specific closed-loop system proves feasible for home use

Author: Sara Freeman


medwireNews: Results of a pilot study show that a hybrid closed-loop insulin delivery system customized for pregnancy (CLC-P) used by women with type 1 diabetes at home significantly improved their glucose outcomes.

Women using the CLC-P spent an average 3.4 more hours per day in target glucose range, a significant increase of 14.1 percentage points, versus using only continuous glucose monitoring during a run-in period. Specifically, women had blood glucose in a recommended target range of 63–140 mg/dL (3.5–7.8 mmol/L) 78.6% of the time when using the system compared with 64.5% of the time during the run-in phase.

The time spent in target glucose range during the night was also increased a significant 23.5 percentage points when CLC-P was used than when it was not, at 84.8% versus 61.3%, Eyal Dassau (Harvard University, Boston, Massachusetts, USA) and collaborators from the LOIS-P Diabetes and Pregnancy Consortium report in Diabetes Care.

But with only 10 patients enrolled, they note that “larger, randomized studies are needed to further evaluate system efficacy and pregnancy outcomes.”

Dassau and team report the first outpatient and extended use of CLC-P in pregnant women with type 1 diabetes. The mean age of the women studied was 32.6 years, they had type 1 diabetes for an average of 16.6 years, an average glycated hemoglobin level of 5.8% at baseline, and all were in the second or early third trimester of their pregnancy.

The run-in phase of the study lasted 1 to 2 weeks, during which time the women used their own personal therapy and continuous glucose monitoring. They then used the CLC-P for 2 days under supervision in an outpatient setting followed by CLC-P use at home from an average gestational age of 23.7 weeks until delivery.

The closed-loop system used consists of a Tandem insulin pump, a continuous glucose monitor, and a zone model predictive control-based algorithm application which runs on an unlocked Android phone. The system calculates the best insulin dose to be delivered every 5 minutes, to keep the blood glucose within a target range of 80–110 mg/dL (4.4–6.1 mmol/L) during the day, and 80–100 mg/dL (4.4–5.6 mmol/L) overnight. 

With CLC-P, women spent significantly less time with blood glucose levels above the highest recommended value of 140 mg/dL (7.8 mmol/L) versus without the system, at 19.7 versus 29.8% of the time.

There was also a significant reduction in the time spent with glucose levels below the lowest recommended value for pregnancy of 63 mg/dL (3.5 mmol/L), as well as below 54 mg/dL (3.0 mmol/L), as compared with the run-in period, with absolute differences of 2.8 and 0.9 percentage points, respectively.

Blood glucose levels were between 63 and 140 mg/dL (3.5–7.8 mmol/L) more than 70% of the time in the majority (90%) of women, Dassau and team highlight.

These results show “that it is feasible to aim for and to achieve pregnancy-specific targets safely in a home setting in the U.S. using a customized hybrid closed-loop system,” they say.

medwireNews is an independent medical news service provided by Springer Healthcare Ltd. © 2023 Springer Healthcare Ltd, part of the Springer Nature Group

Diabetes Care 2023;  doi:10.2337/dc23-0173


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