Aim: The purpose of this study was to investigate how a randomised controlled trial (RCT) of an adapted diabetes nutrition education programme (NEP) was received by adults with sub-optimally controlled (HbA1c of ≥ 8%) type 2 diabetes in a tertiary setting. This could aid in understanding the small effect of NEP on HbA1c and other outcomes and the high attrition rate. Methods: This qualitative study was done alongside the year-long RCT. In the RCT, intervention participants received four NEP components, and both intervention and control group participants received education materials (fridge/wall poster). Five focus-group discussions were held with the intervention group participants at two time periods: after they completed the NEP curriculum (7th month) (n = 26; 67% of randomised participants [RP]( and at the end of the study (12 months) [n = 24; 61.5% RP). Nineteen (50% RP) control group participants were individually interviewed at the end of the study. Data were analysed using a thematic framework. Results: All participants (control and intervention) reported high satisfaction with the NEP. Participants emphasised the value of the fridge/wall poster for themselves and their families. Participants (control and intervention) reported various benefits of the NEP: improved diabetes knowledge, skills in dietary self-care, family support for self-care, better health and motivation for appropriate self-care. Some participants also reported positive changes to their diet and physical activity behaviours. The perceived benefits were the main reason for completing the study. Conclusions: Irrespective of the arm of participation, the NEP was well received, and perceived benefits inspired participation. The limited NEP impact and the sub-optimal programme participation do not appear to be related to participants’ perceptions of the adapted NEP.