Question Does our group-based lifestyle intervention (with or without trained volunteers with Type 2 diabetes) reduce the risk of Type 2 diabetes in people with the current high risk intermediate glycemic categories of impaired fasting glucose or non-diabetic hyperglycemia Finding In this trial of 1,028 participants with high risk intermediate glycemic categories , the intervention significantly reduced the 2 year risk of Type 2 diabetes by 40-47%, although lay volunteer support did not reduce the risk further. For every 11 participants treated, one diabetes diagnosis was prevented. Meaning Nearly half the adult population have diabetes or a high risk glycemic category, and this low-cost group-delivered intervention significantly reduced the risk of diabetes.

ObjectiveIntensive lifestyle interventions reduce the risk of type 2 diabetes in populations at highest risk, but staffing levels are usually unable to meet the challenge of delivering effective prevention strategies to a very large at-risk population. Training volunteers with existing type 2 diabetes to support healthcare professionals deliver lifestyle interventions is an attractive option.MethodsWe identified 141 973 people at highest risk of diabetes in the East of England, screened 12 778, and randomized 1764 into a suite of type 2 diabetes prevention and screen detected type 2 diabetes management trials. A key element of the program tested the value of volunteers with type 2 diabetes, trained to act as diabetes prevention mentors (DPM) when added to an intervention arm delivered by healthcare professionals trained to support participant lifestyle change.ResultsWe invited 9951 people with type 2 diabetes to become DPM and 427 responded (4.3%). Of these, 356 (83.3%) were interviewed by phone, and of these 131 (36.8%) were interviewed in person. We then appointed 104 of these 131 interviewed applicants (79%) to the role (mean age 62 years, 55% (n=57) male). All DPMs volunteered for a total of 2895 months, and made 6879 telephone calls to 461 randomized participants. Seventy-six (73%) DPMs volunteered for at least 6 months and 66 (73%) for at least 1 year.DiscussionIndividuals with type 2 diabetes can be recruited, trained and retained as DPM in large numbers to support a group-based diabetes prevention program delivered by healthcare professionals. This volunteer model is low cost, and accesses the large type 2 diabetes population that shares a lifestyle experience with the target population. This is an attractive model for supporting diabetes prevention efforts.

What is already known on this subject?Many health interventions, including programmes to help prevent or manage diabetes and facilitate weight loss, are delivered in groups. Such group-based behaviour-change interventions are often effective in facilitating psychological and behaviour change. There is considerable research and theory on individual change processes and techniques, but less is known about which change processes and techniques facilitate behaviour change in group settings. What does this study add?This study contributes to our understanding of how participating in group-based health programmes may enhance or impede individual behaviour change. It identified individual (intrapersonal) and group (interpersonal, facilitated through group interaction) change processes that were valued by group participants. The findings also show how these change processes may be affected by the group context. A diagram summarizes the identified themes helping to understand interactions between these key processes occurring in groups.The study offers an insight into participants' views on, and experiences of, attending a group-based diabetes prevention and management programme. Thus, it helps better understand how the intervention might have helped them (or not) and what processes may have influenced intervention outcomes. Key practical recommendations for designing and delivering group-based behaviour-change interventions are presented, which may be used to improve future group-based health interventions.

IntroductionDementia prevalence continues to increase, and effective interventions are needed to prevent, delay or slow its progression. Higher adherence to the Mediterranean diet (MedDiet) and increased physical activity (PA) have been proposed as strategies to facilitate healthy brain ageing and reduce dementia risk. However, to date, there have been no dementia prevention trials in the UK focussed on combined dietary and PA interventions. This study aims to: (1) assess feasibility and acceptability of a theory-underpinned digital and group-based intervention for dementia risk reduction in an ‘at risk’ UK cohort; (2) evaluate behaviour change responses to the intervention; and, (3) provide information on cognitive, neurological, vascular and physiological outcomes to inform the design of a follow-on, full-scale efficacy trial.MethodsOne hundred and eight participants aged 55 to 74 years with a QRISK2 score of ≥10% will be recruited to take part in this 24-week multi-site study. Participants will be randomised into three parallel arms: (1) Control; (2) MedDiet; and, (3) MedDiet+PA. The study will evaluate a personalised website, group session and food delivery intervention to increase MedDiet adherence and PA in older adults at risk of dementia. Diet and PA will be monitored prior to, during and following the intervention. Feasibility, acceptability and hypothesised mediators will be assessed in addition to measures of cognitive function, brain structure/perfusion (MRI), vascular function and metabolic markers (blood, urine and faecal) prior to, and following, the intervention.DiscussionThis trial will provide insights into the feasibility, acceptability and mechanism of effect of a multi-domain intervention focussed on the MedDiet alone and PA for dementia risk reduction in an ‘at risk’ UK cohort.Ethics and disseminationThe study has received NHS REC and HRA approval (18/NI/0191). Findings will be disseminated via conference presentations, public lectures, and peer-reviewed publications.Trial registration detailsClinicalTrials.gov NCT03673722.