Type 1 diabetes (T1D) is a chronic autoimmune disease long thought to primarily affect children and adolescents. However, recent data suggest that nearly 70 percent of new T1D cases occur in adults. Striking differences in genetic, metabolic, and immune features as well as in diabetes management have been described between childhood- and adult-onset T1D, but many of these variances are poorly understood. An improved understanding of childhood- and adult-onset T1D heterogeneity is essential to provide optimal diabetes care but in addition, for designing novel disease-modifying therapies to prevent or arrest ongoing beta cell autoimmunity. I propose to implement the most advanced high-plex in situ assay platforms to study, at gene and protein level, the spatial context and interaction of cellular subtypes in pancreatic tissues obtained from childhood- and adult-onset T1D cases. Integrated data analyses will not only provide novel insights into precise cellular localizations but also identify cellular differentiation / activation states and neighborhoods. This will provide the best map yet of what is occurring in the pancreas at disease onset and how this differs between children and adults. Such knowledge is key to developing new treatments to cure T1D and to better define optimal treatment regimens.