The do-it-yourself artificial pancreas movement, in which users create their own closed-loop insulin delivery systems using commercially available continuous glucose monitoring and insulin pump systems combined with open-source software, is growing, with an estimated 9000 users worldwide despite the systems’ unregulated status. This real-world, observational study compared the efficacy and user characteristics of open-source systems versus the first commercially available hybrid closed-loop system (approved in Europe in 2018).
Data from 68 adults with type 1 diabetes who switched to closed-loop systems from sensor-augmented pump therapy (38 using the commercial system and 30 using various open-source systems) were evaluated. Compared with commercial users, open-source users were younger (age 41 vs 47 years), had a shorter duration of diabetes (25 vs 31 years), were more likely to be male (70% vs 32%), had a lower mean HbA1c at the time of switching (54 vs 62 mmol/mol) and had a higher education status despite similar socio-economic status scores.
Both groups saw their HbA1c fall at 6 months of follow-up, but the open-source group had a greater reduction (9.8 vs 1.1 mmol/mol). The open-source group also had a greater percentage of Time In Range (79% vs 68%) and a lower percentage of Time Above Range (18% vs 29%). However, there was a small but significant increase in time spent with glucose levels <3.0 mmol/L (0.3% vs 0.0%). Open-source users also had higher total daily doses of insulin (0.6 vs 0.5 units/kg) and experienced more weight gain (median weight change +1.25 kg vs –0.3 kg) despite similar reported carbohydrate intake.
The authors observed no safety concerns with the open-source systems; however, the study highlights high rates of out-of-warranty insulin pump use and use of flash glucose monitors with unregulated algorithms.
The authors conclude that do-it-yourself closed-loop insulin delivery systems had a similar efficacy and safety to the commercially approved system, and that these data provide support for the use of these systems in motivated individuals demonstrating a high level of self-care.
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