The United Kingdom Prospective Diabetes Study (UKPDS) is one of the longest and largest clinical trials ever conducted. It explored the effects of intensive blood glucose and blood pressure control on the development of complications in patients with type 2 diabetes. Patients took part in this trial for up to 20 years and the drop-out rate was extremely low. The aim of this discussion paper is to explore patients' motivations for joining the UKPDS and for remaining in the trial, and to examine the implications of findings for good practice before, during, and after clinical trials. A qualitative, exploratory study was undertaken, involving former UKPDS patients (n = 10) at Northampton General Hospital, England. In-depth, semi-structured interviews were undertaken and the data analysed using grounded theory approaches. The results showed that patients were motivated to join the UKPDS because they believed this would give them the best clinical care and reduce the threat of the disease. However, all of the patients identified unanticipated benefits of trial participation, to which they attributed their strong commitment to the UKPDS. These included the reassurance provided by regular clinical examinations, the personal nature of clinical care, and the welcome discipline imposed by UKPDS professionals. Transition back to primary care at trial closure could be a lonely experience, despite follow-up being seen as competent. Practitioners involved in recruiting patients for clinical trials should be aware that participants may be motivated by the desire for better clinical care, irrespective of randomisation consequences. Those taking back the clinical care of trial participants with chronic disease may wish to consider a 're-entry' interview, to minimise trial bereavement.