Type 1 diabetes, also known as juvenile-onset or insulin-dependent diabetes mellitus (IDDM), is caused by destruction of insulin-producing ? cells in the pancreas by the body’s immune system. It affects hundreds of thousands of individuals worldwide, requiring regular insulin injections to control blood glucose levels and avoid severe consequences of glucose dysregulation. Written by experts in the field, this collection from Cold Spring Harbor Perspectives in Medicine provides a detailed examination of our understanding of the disease process and its causes, as well as genetic risk factors, animal models of diabetes, and new treatment strategies that are being developed.