There are currently no clinically precise biomarkers that predict the development of type 1 diabetes (T1D). This limits the ability to identify patients who will become diabetic at a time when they have a greater beta cell mass and thus may respond more favorably to interventional therapeutics aimed at stopping T1D progression. To this end, we propose to identify biomarkers that predict T1D progression by examining exosomes in at-risk and nondiabetic control individuals. Exosomes are small particles released by cells during inflammation that communicate “danger” to other cells nearby and at a distance. Exosomes contain numerous mRNA and miRNA messengers that alter the biology of target cells, which include cells of the innate and adaptive immune systems. We propose to characterize the transcriptional (mRNA and miRNA) contents of exosomes from at-risk and non-diabetic control tissues in order to identify potential biomarkers that predict progression of T1D.