A fully closed-loop insulin delivery approach demonstrated safe and effective glucose control even when adults with type 1 diabetes consumed unannounced, high-carbohydrate and high-fat meals. Published in the Journal of Diabetes Science and Technology, the study evaluated automated insulin delivery performance under conditions that simulate real-world challenges.

Ten adults with type 1 diabetes first completed a home-based run-in period using a hybrid closed-loop system with standard mealtime boluses. They then spent 72 hours in a controlled hotel environment using a fully automated system without meal announcements or bolus dosing. Median meal composition was 70.8 g carbohydrate and 53.2 g fat at breakfast, 53.8 g carbohydrate and 40.0 g fat at lunch, and 96.1 g carbohydrate and 53.1 g fat at dinner. Daily exercise sessions were also included.

The system was active 97.3% of the time and delivered a median time in the range of 61%, compared with 56.3% during the run-in week. Overnight time in range improved markedly to 95.9%, and time below 70 mg/dL was very low at 0.4%. No severe hypoglycemia or diabetic ketoacidosis occurred.

These findings show that fully automated insulin delivery can maintain safe glucose control during unannounced meals and routine activity in adults with type 1 diabetes.