First, to determine the safety of daily oral insulin administration in very young children with high genetic susceptibility for type 1 diabetes; second, to determine whether the previously observed antibody and CD4+ T cell responses to oral insulin could be observed in younger children; third, to explore interactions between oral insulin therapy and INS genotype and microbiome; and, fourth, to investigate immune changes and events that may influence autoimmunity during this period of high susceptibility. Here, INS is linked to type 1 diabetes mellitus.