Type 1 diabetes is a condition that is caused in part by an abnormality of the immune system which occurs when T cells, which are part of the immune system, damage the insulin secreting cells (islet cells) in the pancreas. Although it is known that T cells are important mediators of the disease, progress in the development of reliable T cell assays has been modest. The purpose of this study is to learn which T cell assays are most reliable and reproducible so that the investigators can improve their understanding about how type 1 diabetes occurs.