Natural History of Autoimmune Diabetes and Its Complications

Background: * Diabetes is a disease defined by abnormally high blood sugar (glucose) levels. Glucose is an essential source of energy for the body s cells, but insulin is required to move the glucose into the cells. Insulin is a hormone produced by the pancreas that allows glucose to enter cells. * In diabetes, the body is unable to supply enough insulin to meet its demands. The problem may be a low supply of insulin or a high demand for insulin. Someone who has been diagnosed with diabetes has lost much of their insulin-producing capacity. Clinical studies have shown that good control of blood sugar is essential to prevent diabetes complications like damage to the eyes, kidneys, nerves, and blood vessels. Objectives: * To establish a relationship with several individuals with diabetes caused by the immune system attacking the body s insulin-producing cells in order to: * Explore why the immune system attacks insulin-producing cells. * Understand why some individuals develop diabetes-related complications and others do not. * Develop therapies to improve how patients can control their blood sugar levels. * Continue to follow subjects who have completed or are considering other NIH diabetes-related studies. * To develop improved tests for determining an individual s risk for developing diabetes and/or to accurately diagnose the exact type of diabetes. Eligibility: * Individuals who have been diagnosed with or are at risk for developing diabetes. Design: * Standard physical examination and clinical tests to determine if the patient has diabetes or to confirm a particular type of diabetes: * None of the treatment in this study is experimental. * Patients will receive a separate consent form for any special tests needed to learn more about their particular type of diabetes. * Patients may be asked to provide additional urine and blood samples for use in laboratory research about diabetes. * Researchers may offer medical treatment advice for diabetes, or explain how to improve patients diabetes management skills.