Background <p>Cystic fibrosis-related diabetes (CFrD) is a common complication of cystic fibrosis (CF). Many people with CFrD struggle to keep glucose within target range leading to poorer clinical outcomes and reduced life expectancy. Hybrid closed-loop (HCL) systems are an exciting innovation which may help people with CFrD improve their glucose management and experience a better quality-of-life. We explored the experiences of adults with CFrD who used the CamAPS FX HCL to: understand the benefits and challenges to using HCL in people with CFrD; and, help inform decision-making about HCL use in CFrD populations in routine clinical care.</p> Methods <p>We interviewed 19 individuals who used the CamAPS FX HCL for ≥ 3 months during the CL4P-CF clinical trial. Data were analysed thematically.</p> Results <p>Participants reported multiple clinical and quality-of-life benefits to using HCL. Many described treatment burnout before using the system and, hence, benefitting from automated glucose regulation and an increased capacity to take on new activities. Participants also shared historical difficulties gaining/maintaining weight as a result of their CF and described how using the system helped them achieve weight/muscle gain, improved their bodily confidence and enabled to them to enjoy a greater diversity of foods. Participants also observed CF-related benefits, including a (perceived) reduced susceptibility to infections, improved mood/energy to take on CF management-tasks, and increased confidence and ability to undertake physical activity due to a reduced risk of hypoglycaemia. In addition, participants reported medical trauma arising from hospital admissions in childhood and exposure to medically-invasive procedures for their CF, and highlighted benefits to using a system which mitigated the need to use injections. Due to their earlier traumatic experiences, some expressed a preference for using tubeless pumps and cannulas that require less frequent replacement.</p> Conclusions <p>Participants reported improved glucose management, CF-related benefits and wide-ranging quality-of-life gains resulting from HCL use. Given their earlier experiences of treatment burnout and medically-related trauma, and taking account of the distinctive challenges involved in managing CFrD, our findings suggest that people with CFrD are a uniquely deserving group for access to HCL technology if shown to be clinically and cost effective in this population.</p> Trial registration <p>ClinicalTrials.gov: NCT05562492, registration date 28th September 2022.</p>