Fully closed‑loop systems: can people with type 1 diabetes just do it? Insights from open‑source systems – Published online 19/01/2026

Rayhan Lal, Katarina Braune, Dana M. Lewis, Lenka Petruzelkova, Martin de Bock, Sufyan Hussain

 The dream of so-called ‘fully closed-loop’ insulin delivery requires no interaction from the end user, removing all burden from them. While we are still far from that goal, interim steps such as removing meal announcements from automated insulin dosing systems would provide a clear reduction in burden for users. The OpenAPS algorithm is the only widely disseminated automated insulin dosing approach that supports unannounced meals. In this issue, Lal et al (https://doi.org/10.1007/s00125-025-06644-8) review emerging clinical evidence alongside user and healthcare professional experiences, and present insights into the use of this system without meal announcements for people with diabetes. The authors discuss that once this more proximal goal is met, further work will be required to remove the need for announcements of any kind (e.g. exercise and acute changes in insulin sensitivity). They conclude that true fully closed-loop systems should require no interaction with the system by the end user, and may not take the form of automated insulin delivery as we know it today. The figures from this review are available as a downloadable slideset.

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