The characterization of dendritic cells (DCs) in diabetes has primarily examined in vitro-generated DCs. In this study, we have compared the composition and phenotype of naturally occurring DCs within the peripheral blood of subjects with type 1 diabetes, latent-onset autoimmune diabetes in adults, and nondiabetic controls. We find that circulatory DC subsets exist in normal frequencies and phenotypic states in diabetic patients. In vivo, DCs were located around the pancreatic islets in type 1 diabetic patients, but were absent in pancreatic tissue of normal controls. These findings provide new insight toward understanding the pathological role of DCs in type 1 diabetes.