Aims To study the reasons for attendance behaviour from the patient viewpoint at a young adult diabetes outpatient clinic. Methods Attendance rates for 231 clinic appointments over 19 months for 102 patients were calculated. Semi-structured interviews were conducted with a purposive sample of 17 of the 102. The interviews encouraged participants to describe routines, thoughts and feelings around clinic appointments. Observations were made of the clinic system. Themes arising from patients emotional and practical issues around attendance were generated from the data. Results Did not attend rates for the clinic over the study period were 15.7%. However, bureaucratic problems created many missed appointments; most instances of did not attend investigated were attributable to communication failures. Participants did not divide neatly into attenders/non-attenders; many had complex mixed attendance records. Most weighed the value of attendance against immediate obstacles such as incompatible work/clinic hours. Reminders were seen as important, particularly for this age group. Respondents identified fear of being judged for poor control as a major factor in attendance decisions, suggesting that having a high HbA1c level may lead to non-attendance, rather than vice versa. Conclusions Health professionals supportive, non-judgemental attitude is important to patients considering clinic attendance. In this study, improved communication, reminders and flexible hours might reduce did not attend rates.