Type 2 diabetes prevention programs at the community and municipal level: a scoping review of controlled intervention studies

BACKGROUND: Type 2 diabetes mellitus poses a major challenge to public health globally due to its rising prevalence and high proportion of patients who are undiagnosed, untreated and/or uncontrolled. Lifestyle interventions targeting nutrition, physical activity, and further health-related behaviors such as weight and stress management can prevent the onset of type 2 diabetes mellitus or delay progression from prediabetes to manifest disease. Although lifestyle interventions are widely used in clinical trials and national programs, there is limited evidence on how such interventions are designed, adapted, and reported in community, municipal, and public health settings. METHODS: A scoping review was conducted using the Population Concept Context framework. Systematic searches were performed in PubMed, Web of Science Core Collection, CINAHL, and CENTRAL. The CDSR was used for citation tracking to identify relevant primary studies. Additional searches included grey literature, organizational websites, and an AI-assisted search (undermind.ai). Searches covered studies published in English or German between January 2014 and May 2025 and were conducted on 28 May 2025. Eligible studies examined lifestyle-based interventions targeting physical activity, nutrition, or broader behavioral change among healthy adults and adults at increased risk of developing type 2 diabetes, including individuals with prediabetes or metabolic syndrome, delivered in community, municipal, or public health settings. Inclusion was restricted to controlled study designs ((cluster-)randomized controlled trials, non-randomized controlled studies, or controlled clinical trials). Feasibility studies, pilot studies, uncontrolled implementation studies, and process evaluations were excluded. Pharmacological interventions were not considered. Data were charted and synthesized descriptively. RESULTS: Of 464 records identified, 26 studies were included. Interventions were largely adapted from established prevention programs and delivered through group-based education, with limited reporting of theoretical frameworks. Definitions and operationalization of "community-based" delivery varied across studies, and intervention duration and maintenance components were heterogeneous. The evidence base was dominated by studies conducted in high-income countries, with limited representation from lower-resource settings. CONCLUSIONS: This scoping review highlights the need for greater representation of studies from lower-resource settings and theoretically grounded and methodologically rigorous prevention approaches in the community setting. The potential of community-based initiatives offers valuable guidance for further development and scaling future diabetes prevention efforts. TRIAL REGISTRATION: Open Science Framework (osf.io/zafg5).