Aim: To explore how participating in a randomised controlled trial affected motivation, barriers and strategies in the process of health behaviour change among individuals with prediabetes. Methods: An extension to the PRE-D trial, a qualitative study investigated the efficacy of glucose-lowering interventions (metformin, dapagliflozin or exercise) compared with a control group among individuals with prediabetes and overweight/obesity. Data were collected through separate focus group interviews with participants using semi-structured interview guides inspired by health behaviour change theories. Interviews were audio-recorded, transcribed verbatim and analysed using thematic analysis with an inductive-deductive approach. Results: Four interrelated themes emerged from interviews: (1) 'self-construction of prediabetes', on how participants understood the term 'prediabetes', (2) 'altered health image', on how participants' health perceptions were affected, (3) 'personal strategies for health behaviour change', on different ways to attempt to implement behaviour changes and (4) 'the process of health behaviour change', on how participants progressed and relapsed while trying to change behaviour. Themes relate to the health belief model, self-determination theory, self-efficacy and the trans-theoretical model of change. Participants shared their experiences and thoughts during interviews and inspired each other, which led some participants to develop a new perspective on prediabetes severity and increased their motivation for behaviour change. Conclusions: How participants perceived and accepted, rejected or neglected prediabetes appeared to affect their health images and whether they realised a need for behaviour change. Their achievements during interventions, health literacy, self-efficacy and perceived support from their social networks, professionals and technological aids influenced the maintenance of health behaviour changes.