IL2 and type 1 diabetes mellitus: Being able to conclude confidently that LD IL-2 administration is efficacious and safe for patients with T1D, we need reliable and robust immune biomarkers and assays that (1) will help to stratify the study population and (2) predict at which stage of disease progression the administration of LD IL-2 alone or in combination with an antigen-specific therapy will be efficacious in curing or preventing T1D.