This study is essentially a long-term observational study of the subjects who participated in the Diabetes Control and Complications Trial (DCCT). Assessment of subjects' eyes, kidneys, and vascular system will be made every 1-5 years using techniques previously used in the DCCT. The only exception to this will be that carotid ultrasound measurements will be carried out every 5 years to assess the effects of diabetes treatment on the development of macrovascular disease.