Abstract: Aims: To undertake a feasibility randomized controlled trial of supported self‐management vs treatment as usual in a population of adults with obesity, Type 2 diabetes and an intellectual disability. Methods: We conducted an individually randomized feasibility trial. Participants were adults aged >18 years with a mild or moderate intellectual disability, living in the community with Type 2 diabetes, on any therapy other than insulin. Participants had mental capacity to consent to research and the intervention. Inclusion criteria included HbA1c > 48 mmol/mol (6.5%), BMI >25 kg/m2, or self‐reported physical activity below national guideline levels. The experimental intervention was standardized supported self‐management delivered by diabetes specialist nurses plus treatment as usual, compared with treatment as usual alone. Feasibility outcomes included: recruitment and retention; intervention acceptability and feasibility; data collection and completeness for physiological state and values for candidate primary outcomes (HbA1c and BMI). Results: A total of 82 participants (89% of those contacted and eligible) were randomized. All supported self‐management sessions were completed by 35/41 participants (85%); only four completed no sessions. Data on the follow‐up candidate primary outcomes HbA1c and BMI were obtained for 75/82 (91%) and 77/82 participants (94%), respectively. The mean baseline HbA1c was 56±16.5 mmol/mol (7.3±1.5%) and the mean BMI was 34±7.6 kg/m2. Conclusions: Adherence to supported self‐management and willingness to have blood taken for outcome measurement was good. A definitive randomized controlled trial is feasible in this population. (Trial registration: Current Controlled Trials ISRCTN41897033) [ABSTRACT FROM AUTHOR]