The study was a population-based, longitudinal, cohort study to determine the prevalence and incidence rates of cardiovascular disease morbidity and mortality in people with Type 1 diabetes of long duration. The mean age of the cohort and the long duration of diabetes provided an opportunity to document the prevalence and incidence of coronary heart disease, myocardial infarction, angina, congestive heart failure, stroke, transient ischemic attacks, peripheral vascular disease and cardiovascular disease mortality in a large population-base group of persons with Type 1 diabetes. Standardized protocols for exams and interviews were used during the baseline, 4-, 10-, and 14-year follow-up exams. Retinal photographs of each study participant were taken at the baseline examination. This permitted the investigators to test the predictive ability of focal and generalized retinal arteriolar narrowing and arteriovenous crossing changes (i.e., A/V nicking) for subsequent macrovascular events controlling for other risk factors. These factors included blood pressure, cigarette smoking, serum lipids, body mass index, duration of diabetes, and glycemia.