For a study, researchers sought to determine if the relative availability of fast-food restaurants and supermarkets mediates the link between poor neighborhood socioeconomic conditions and the prevalence of type 2 diabetes (T2D). About 3 academic institutions used harmonized environmental data sources and analytic methods in 3 different study samples as part of the Diabetes Location, Environmental Attributes. Disparities Network: the Veterans Administration Diabetes Risk (VADR) cohort, a national administrative cohort of 4.1 million diabetes-free veterans developed using electronic health records (EHRs); Reasons for Geographic and Racial Differences in Stroke (REGARDS), a longitudinal epidemiologic cohort with Stroke Belt region oversampling (N=11,208); and Geisinger/Johns Hopkins University (G/JHU), a nested case-control study of 15,888 patients with new-onset T2D and of matched control participants in Pennsylvania. As a community type-specific z-score sum, a census tract–level measure of neighborhood socioeconomic environment (NSEE) was devised. The percentages of fast-food restaurants and food retail businesses that were supermarkets were used as baseline food-environment mediators. The results were stratified among 4 community types: higher-density urban, lower-density urban, suburban/small town, and rural. In multiple investigations, a higher NSEE was linked to a higher risk of T2D. The relative abundance of fast-food restaurants and supermarkets was found to be positively and negatively correlated with T2D in VADR, although relationships in REGARDS and G/JHU geographies were ambiguous. The mediation analysis results revealed that food-environment pathways mediated little to none of the NSEE–diabetes correlations. Higher T2D risk was linked to worsening neighborhood socioeconomic conditions, although these links were unlikely to be mediated by food-environment pathways.