Objectives and design Lifestyle interventions can prevent type 2 diabetes (T2D) in adults with impaired glucose tolerance. In a mixed methods pilot study, we aimed to assess the feasibility, acceptability and outcomes at a 12-month follow-up of a behavioural intervention for adults at risk of T2D.

Participants Adults aged 45–65 years with a Finnish Diabetes Risk Score (FINDRISC) ≥11.

Setting The intervention was delivered in leisure and community settings in a local authority that ranks in the 10 most socioeconomically deprived in England.

Intervention A 10-week supported programme to promote increased physical activity (PA), healthy eating and weight loss was delivered by fitness trainers as twice-weekly group PA or cookery sessions, each followed by behavioural counselling with support to 12 months.

Outcome measures We assessed feasibility and acceptability of the intervention, and change in behavioural and health-related outcomes at 6 and 12 months.

Results From 367 registers of interest, 218 participants were recruited to the programme with baseline mean (SD): age 53.6 (6) years, FINDRISC 13.9 (3.1), body mass index 33.5 (5.9) kg/m², waist circumference 108.1 (13.7) cm, PA levels (self-report): daily total 49.1 (5.9) metabolic-equivalent (MET) h/day. Follow-up at 12 months was completed by 134 (61%) participants, with an estimated mean (95% CI) change from baseline in weight −5.7 (−7.8 to −2.8); −2.8 (−3.8 to −1.9) kg, waist circumference −7.2 (−9.2 to −5.2); −6.0 (−7.1 to −5.0) cm, and PA level 7.9 (5.8 to 10.1); 6.7 (5.2 to 8.2) MET h/day equivalent, for men and women, respectively (from covariance pattern mixed models). Participants reported an enjoyable, sociable and supportive intervention experience.

Conclusions Participants’ views indicated a high level of intervention acceptability. High retention and positive outcomes at 12 months provide encouraging indications of the feasibility and potential effectiveness of the intervention. A definitive trial of this intervention is warranted.