Neighborhood characteristics and lifestyle intervention outcomes: Results from the Special Diabetes Program for Indians.

Growing evidence reveals various neighborhood conditions are associated with the risk of developing type 2 diabetes. It is unknown, however, whether the effectiveness of diabetes prevention interventions is also influenced by neighborhood characteristics. The purpose of the current study is to examine the impact of neighborhood characteristics on the outcomes of a lifestyle intervention to prevent diabetes in American Indians and Alaska Natives (AI/ANs). Year 2000 US Census Tract data were linked with those from the Special Diabetes Program for Indians Diabetes Prevention Program (SDPI-DP), an evidence-based lifestyle intervention implemented in 36 AI/AN grantee sites across the US. A total of 3394 participants started the intervention between 01/01/2006 and 07/31/2009 and were followed by 07/31/2016. In 2016-2017, data analyses were conducted to evaluate the relationships of neighborhood characteristics with intervention outcomes, controlling for individual level socioeconomic status. AI/ANs from sites located in neighborhoods with higher median household income had 38% lower risk of developing diabetes than those from sites with lower neighborhood income (adjusted hazard ratio = 0.65, 95% CI: 0.47-0.90). Further, those from sites with higher neighborhood concentrations of AI/ANs achieved less BMI reduction and physical activity increase. Meanwhile, participants from sites with higher neighborhood level of vehicle occupancy made more improvement in BMI and diet. Lifestyle intervention effectiveness was not optimal when the intervention was implemented at sites with disadvantaged neighborhood characteristics. Meaningful improvements in socioeconomic and other neighborhood disadvantages of vulnerable populations could be important in stemming the global epidemic of diabetes.