Glycemic variability and quality of life outcomes after changing to hybrid closed-loop system in Japanese individuals with type 1 diabetes using a conventional predictive low-glucose suspended insulin pump system

The hybrid closed-loop (HCL) system, Medtronic MiniMed^™ 770G, has been available for use by Japanese individuals with type 1 diabetes mellitus since 2021. The aim of this study was to evaluate the effect of its use on glycemic variability and quality of life (QOL) in this population. This multicenter, open-label, prospective observational study included 14 Japanese individuals with type 1 diabetes mellitus treated with MiniMed^™ 640G. Participants who switched to the 770G system were evaluated for time in range (TIR) and other glycemic outcomes at baseline and at 3 and 12 months post-transition. QOL was assessed using the Diabetes Therapy-Related QOL (DTR-QOL) scale. The mean baseline glycated hemoglobin was 7.52 ± 1.05%, and body mass index (BMI) was 21.78 ± 3.07 kg/m². By study completion, individuals used the HCL system approximately 80% of the time in a day. TIR showed improvement, with an increased achievement ratio of TIR > 70% at 12 months. Hypoglycemia occurrence was minimal at 12 months. In addition, all-time sensor glucose measurements decreased after 12 months, and there were no significant changes in BMI or daily insulin dose. DTR-QOL scores did not significantly differ, possibly owing to increased total alarms and sensor calibration times. Transitioning to the Medtronic MiniMed^™ 770G system led to an improved achievement ratio of TIR > 70% and reduced hyperglycemia at 12 months. However, no significant change in QOL was observed, probably because of the increased number of total alarms.