Automated closed-loop insulin delivery for the management of type 1 diabetes during pregnancy: the AiDAPT RCT
Authors: Lee Tara TM , Collett Corinne , Bergford Simon , Hartnell Sara , Scott Eleanor M , Lindsay Robert S , Hunt Katharine F , McCance David R , Barnard-Kelly Katharine , Rankin David , Lawton Julia , Reynolds Rebecca M , Flanagan Emma , Hammond Matthew , Shepstone Lee , Wilinska Malgorzata E , Sibayan Judy , Kollman Craig , Beck Roy , Hovorka Roman , Murphy Helen R 
Published: May 2024

Background
There are over 2000 pregnancies annually in women with type 1 diabetes in the UK. Despite recent improvements in diabetes technology, most women cannot achieve and maintain the recommended pregnancy glucose targets. Thus, one in two babies experience complications requiring neonatal care unit admission. Recent studies demonstrate that hybrid closed-loop therapy, in which algorithms adjust insulin delivery according to continuous glucose measurements, is effective for managing type 1 diabetes outside of pregnancy, but efficacy during pregnancy is unclear.

Objective
To examine the clinical efficacy of hybrid closed-loop compared to standard insulin therapy in pregnant women with type 1 diabetes.

Design
A multicentre, parallel-group, open-label, randomised, controlled trial in pregnant women with type 1 diabetes.

Setting
Nine antenatal diabetes clinics in England, Scotland and Northern Ireland.

Participants
Pregnant women with type 1 diabetes and above-target glucose levels, defined as glycated haemoglobin A1c of ≥ 48 mmol/mol (6.5%) in early pregnancy.

Interventions
A hybrid closed-loop system compared to standard insulin delivery (via insulin pump or multiple daily injections) with continuous glucose monitoring.

Outcome measures
The primary outcome is the difference between the intervention and control groups in percentage time spent in the pregnancy glucose target range (3.5–7.8 mmol/l) as measured by continuous glucose monitoring from 16 weeks’ gestation until delivery. Secondary outcomes include overnight time in range, time above range (> 7.8 mmol/l), glycated haemoglobin A1c, safety outcomes (diabetic ketoacidosis, severe hypoglycaemia, adverse device events), psychosocial functioning obstetric and neonatal outcomes.

Results
The percentage of time that maternal glucose levels were within target range was higher with closed-loop than standard insulin therapy: 68.2 ± 10.5 in closed-loop and 55.6 ± 12.5 in the control group (mean‑adjusted difference 10.5 percentage points, 95% confidence interval 7.0 to 14.0; p < 0.001). Results were consistent in secondary outcomes, with less time above range (−10.2%, 95% confidence interval −13.8 to −6.6%; p < 0.001), higher overnight time in range (12.3%, 95% confidence interval 8.3 to 16.2%; p < 0.001) and lower glycated haemoglobin A1c (−0.31%, 95% confidence interval −0.50 to −0.12%; p < 0.002) all favouring closed-loop. The treatment effect was apparent from early pregnancy and consistent across clinical sites, maternal glycated haemoglobin A1c categories and previous insulin regimen. Maternal glucose improvements were achieved with 3.7 kg less gestational weight gain and without additional hypoglycaemia or total daily insulin dose. There were no unanticipated safety problems (six vs. five severe hypoglycaemia cases, one diabetic ketoacidosis per group) and seven device-related adverse events associated with closed-loop. There were no between-group differences in patient-reported outcomes. There was one shoulder dystocia in the closed-loop group and four serious birth injuries, including one neonatal death in the standard care group.

Limitations
Our results cannot be extrapolated to closed-loop systems with higher glucose targets, and our sample size did not provide definitive data on maternal and neonatal outcomes.

Conclusions
Hybrid closed-loop therapy significantly improved maternal glycaemia during type 1 diabetes pregnancy. Our results support National Institute for Health and Care Excellence guideline recommendations that hybrid closed-loop therapy should be offered to all pregnant women with type 1 diabetes.

Future work
Future trials should examine the effectiveness of hybrid closed-loop started before pregnancy, or as soon as possible after pregnancy confirmation.

Trial registration
This trial is registered as ISRCTN56898625.

Funding
This award was funded by the National Institute of Health and Care Research (NIHR) Efficacy and Mechanism Evaluation (EME) programme (NIHR award ref: 16/35/01) and is published in full in Efficacy and Mechanism Evaluation; Vol. 11, No. 7. See the NIHR Funding and Awards website for further award information.
Dexcom supplied the continuous glucose monitoring systems used by AiDAPT intervention- and control-arm participants at reduced cost.