Introduction

With 96 million American adults living with prediabetes and 5–10% of these individuals develo** type 2 diabetes mellitus (T2DM) each year, increased dissemination of evidence-based T2DM prevention interventions is imperative (Glechner et al., 2018). The Centers for Disease Control and Prevention’s (CDC) National Diabetes Prevention Program (DPP) aims to increase screening for and detection of prediabetes and T2DM and to increase dissemination of and access to the diabetes prevention. The DPP is a 12-month lifestyle change intervention designed to reduce T2DM risk through diet, exercise, and lifestyle changes (Knowler et al., 2002, 2009). DPP clinical trials resulted in reduced rates of T2DM up to 58% in individuals with prediabetes (Allaire et al., 2020; Knowler et al., 2002, 2009). Since the initial DPP clinical trial, nearly 20 years of translational research has demonstrated similar results can be achieved using trained lay leaders in a variety of settings if critical components are upheld (i.e., use of approved curriculum, program duration, frequency of sessions) (Centers for Disease Control and Prevention, 2018; Ali et al., 2012).

Cooperative Extension (here forth, “Extension”), with its over 100-year history of providing health education interventions, presence in almost every county in every state, and trained personnel (i.e., state-level Extension leaders with health program implementation expertise: Extension Specialists), is poised as an effective platform for DPP dissemination and implementation (Franz & Townson, 2008; Molgaard, 1997). In the state of Georgia, there are 159 counties, with 57 having a county-based Extension professional that specializes in health and wellness (University of Georgia, 2023). At present, 31 Extension organizations, representing 17 U.S. states, are CDC-recognized DPP providers (CDC, 2023). While this number is growing, this is far fewer than the potential 50 states and additional U.S. territories that could be DPP providers.

While CDC is tracking overall effectiveness of the DPP among CDC-recognized providers (Ely et al., 2017), little is known about context-specific effectiveness and implementation and which organization types are uniquely positioned to succeed in effective and sustainable DPP delivery. Damschroder et al. (2017a). DPP marketing efforts to potential participants, community partners, and even potential program implementers should emphasize the DPP as a CDC, evidence-based program to improve buy-in. Extension professionals’ perceived “fit” of the DPP with Extension’s mission and programming, along with the present study’s high adoption rate, supports the value of Extension as a delivery system to increase dissemination of the DPP. When asked about increasing adoption of the DPP in other counties throughout the state, Extension professionals felt that success stories from the implementation pilot, the support provided for implementation, and the value of the DPP’s evidence base for building community rapport and Extension professionals’ impact statements would be incentives for adoption by other counties. Still, Extension professionals noted that adoption would be limited to counties with Extension professionals. With the number of county Extension professionals decreasing, considerations on how to maintain the strong adoption observed in the present study and how to promote reach throughout the state should be made in light of these realities. Delivery during the COVID-19 pandemic highlighted the value of virtual delivery for accessing residents in counties without county-based Extension professionals. Virtual delivery should be explored in the future to overcome potential adoption and reach barriers.

Extension leadership contributed to the professionals’ knowledge of the DPP and decision to adopt the program. Compared to other settings in which the DPP might be implemented, the support infrastructure of Extension further positions it to be a strong delivery system (Franz & Fahey, 2012; Franz & Townson, 2008; Franz et al., 2010). Most Extension organizations have a nutrition and/or health Extension Specialist that provides access to expertise in DPP-related content areas (Harden et al., 2019), administrative oversight, and implementation support. Still, depending on the Extension structure, some Extension Specialists are assigned to several programs and may have limited time to support a single, complex program like the DPP. This barrier is not specific to Extension, as Damschroder et al. (2017a) cited similar challenges in the VA context. Extension professionals discussed the need for a permanent DPP coordinator to assist the Extension Specialist to overcome this challenge. CDC does suggest that programs have an assigned DPP coordinator. In small organizations, this may be particularly challenging; but in larger organizations like Extension, a staff member or graduate student can be assigned to this role, as in the case of our study.

Implementation Strategies Utilized

Implementation strategies, including technical assistance calls, created a positive learning climate that Extension professionals felt facilitated implementation. These results echo those reported by Damschroder et al., who also used bi-weekly meetings to provide pertinent updates and information and problem-solve issues (Damschroder et al., 2017a). Extension professionals also spoke to the value of the additional day of training held after the lifestyle coach training. Damschroder et al. also found leadership involvement and support to be one of the most important facilitators of DPP implementation in the VA context (Damschroder et al., 2017a). For multisite DPP delivery systems, additional training on implementation protocols specific to that delivery system may be beneficial for optimizing outcomes. Continued support from leaders in the form of consistent communication and continuing education were all cited as important components of implementation that would be important for maintenance as well as expansion of the DPP into other counties. These consistencies noted between the present and Damschroder et al., (2015, 2017a) studies indicate that the implementation strategies utilized in both (technical assistance calls, leadership involvement, training) may promote implementation outcomes across multiple contexts.

Limitations and Strengths

The present study is not without limitations. Notably, no control or comparison group was included to allow for either comparison of implementation outcomes with and without the utilization of implementation strategies, or comparison of barriers and facilitators presented by the context of Extension compared to another context, limiting conclusions that can be made from the presented results. Still, comparisons to the most comparable literature to date (Damschroder et al., 2017a) have been made throughout. Many of the implementation strategies employed in this study involved state-level leadership support and training for Extension professionals. Withholding support and training from Extension professionals is not acceptable in the setting of Extension, making comparison of outcomes with and without these implementation strategies not feasible. Future studies should consider testing different implementation strategies side by side (e.g., one-on-one technical assistance verses group-based technical assistance) and/or comparison of implementation barriers and facilitators within and outside Extension.

In addition, the research team involved in data collection and analysis was heavily involved in supporting program implementation, potentially introducing researcher bias. However, the familiarity of the researchers with the implementation process offered a more comprehensive understanding of the topics discussed in interviews. Furthermore, three of the five data analysts were not involved in supporting implementation. Additionally, no objective measure of fidelity was included in the present study. Lastly, the number of counties/Extension professionals included in the present study was limited, compared to the total possible sample size in the state of Georgia. The initial sample was limited to meet financial constraints and assess initial feasibility in the pilot implementation study. Counties and Extension professionals from every region of the state, as well as both rural and urban counties, were included in an effort to increase the generalizability of the results.

There are also several strengths. This study is unique in its contribution to the literature by using standard frameworks (CFIR and RE-AIM) to rigorously evaluate implementation of an evidence-based program in a community setting that is well positioned to be an established DPP provider: Extension. Integration of the CFIR with RE-AIM also increases the translational value of this study, as the barriers and facilitators of RE-AIM identified using the CFIR in this study provide a foundation on which implementation strategies can be built to potentially enhance RE-AIM outcomes of the DPP in Extension and potentially other community contexts.

Conclusions

Although freely available, the Diabetes Prevention Program is a complex intervention with many considerations for enhancing dissemination and implementation to reduce the public health burden of T2DM. Using the CFIR and RE-AIM frameworks, this study demonstrated similar reach, effectiveness, adoption and maintenance in Extension to DPP implementation in clinical contexts, and revealed Extension-system specific facilitators of RE-AIM outcomes. The supportive leadership structure, with state-level Extension Specialists and local community health educators (Extension professionals), compatible mission, access to content and implementation expertise, and established communication channels were discussed as benefits of this organizational structure. The strong Implementation, Adoption, and Maintenance observed in this study support the value of Extension as an effective and sustainable delivery system for the DPP. Future research should use similar methods to explore implementation in Extension and other contexts across the U.S. to further test the promising implementation strategies utilized in this study that promote communication and access to information, resources, and support to promote uptake and implementation of the DPP in Extension and beyond.