BackgroundObesity and type 2 diabetes are common in adults with a learning disability. It is not known if the principles of self-management can be applied in this population.ObjectivesTo develop and evaluate a case-finding method and undertake an observational study of adults with a learning disability and type 2 diabetes, to develop a standardised supported self-management (SSM) intervention and measure of adherence and to undertake a feasibility randomised controlled trial (RCT) of SSM versus treatment as usual (TAU).DesignObservational study and an individually randomised feasibility RCT.SettingThree cities in West Yorkshire, UK.ParticipantsIn the observational study: adults aged > 18 years with a mild or moderate learning disability, who have type 2 diabetes that is not being treated with insulin and who are living in the community. Participants had mental capacity to consent to research and to the intervention. In the RCT participants had glycated haemoglobin (HbA1c) levels of > 6.5% (48 mmol/mol), a body mass index (BMI) of > 25 kg/m2or self-reported physical activity below national guideline levels.InterventionsStandardised SSM. TAU supported by an easy-read booklet.Main outcome measures(1) The number of eligible participants identified and sources of referral; (2) current living and support arrangements; (3) current health state, including level of HbA1c, BMI and waist circumference, blood pressure and lipids; (4) mood, preferences for change; (5) recruitment and retention in RCT; (6) implementation and adherence to the intervention; (7) completeness of data collection and values for candidate primary outcomes; and (8) qualitative data on participant experience of the research process and intervention.ResultsIn the observational study we identified 147 eligible consenting participants. The mean age was 54.4 years. In total, 130 out of 147 (88%) named a key supporter, with 113 supporters (77%) being involved in diabetes management. The mean HbA1clevel was 54.5 mmol/mol [standard deviation (SD) 14.8 mmol/mol; 7.1%, SD 1.4%]. The BMI of 65% of participants was > 30 kg/m2and of 21% was > 40 kg/m2. Many participants reported low mood, dissatisfaction with lifestyle and diabetes management and an interest in change. Non-response rates were high (45/147, 31%) for medical data requested from the primary care team. In the RCT, 82 participants were randomised. The mean baseline HbA1clevel was 56 mmol/mol (SD 16.5 mmol/mol; 7.3%, SD 1.5%) and the mean BMI was 34 kg/m2(SD 7.6 kg/m2). All SSM sessions were completed by 35 out of 41 participants. The adherence measure was obtained in 37 out of 41 participants. The follow-up HbA1clevel and BMI was obtained for 75 out of 82 (91%) and 77 out of 82 (94%) participants, respectively. Most participants reported a positive experience of the intervention. A low response rate and difficulty understanding the EuroQol-5 Dimensions were challenges in obtaining data for an economic analysis.LimitationsWe recruited from only 60% of eligible general practices, and 90% of participants were on a general practice learning disability register, which meant that we did not recruit many participants from the wider population with milder learning disability.ConclusionsA definitive RCT is feasible and would need to recruit 194 participants per arm. The main barrier is the resource-intensive nature of recruitment. Future research is needed into the effectiveness of obesity treatments in this population, particularly estimating the longer-term outcomes that are important for health benefit. Research is also needed into improving ways of assessing quality of life in adults with a learning disability.Trial registrationCurrent Controlled Trials ISRCTN41897033.FundingThis project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full inHealth Technology Assessment; Vol. 22, No. 26. See the NIHR Journals Library website for further project information.