Type 1 diabetes results from the autoimmune destruction of the insulin-producing beta cells of the islets of Langerhans of the pancreas. Initially, diabetes is usually clinically silent with immune cells invading the pancreatic islets, a process termed insulitis, which eventually leads to loss of beta cells in the islets. If enough beta cells are destroyed, the body can not make enough insulin to maintain blood sugars in the normal range and clinical diabetes develops. The purpose of this study is to assess the ability of magnetic resonance imaging with ferumoxytol to detect changes in the pancreas associated with the insulitis of type 1 diabetes.