Self-management support interventions for type 2 diabetes can help improve outcomes for people with Type 2 diabetes. However, difficulties in sustaining self-management behaviours attenuate long-term impact, with long term studies showing that people tend to experience a decline in glycaemic control over time, particularly from 6 months to a year post-intervention. Research has suggested that this decline might be due to the characteristics of current interventions, which tend to overlook the development of skills necessary to adapt behaviours to the different demands of the condition and everyday life, and that follow-up support might be needed to prevent a decline in glycaemic control. Nevertheless, little is known about why people struggle to maintain self-management behaviours and how can interventions better support them to maintain effective type 2 diabetes self-management in the long term. This research aims to address this gap by combining international evidence with stakeholder expertise using a behavioural science approach.