The purpose of this research is to assess the long term effects of Insulin Dependent Diabetes Mellitus (IDDM) on learning in children. It has been hypothesized that chronic fluctuations in blood sugar levels can produce cognitive deficits over time, but the use of selective clinical samples and inadequate controls has led to inconsistent findings in prior studies. The specific aims of this study are to determine whether IDDM significantly interferes with the development of long term academic performance and to identify disease-related variables or background factors that lead to increased risk for academic problems. Recruitment will include the majority of school age children with IDDM in the state of Iowa, resulting in a large and representative sample (N>400) whose academic performance will be compared to both siblings and classmate controls on standardized achievement test administered routinely throughout the state. Both cross sectional and longitudinal comparisons will be carried out, using growth curve analyses with the longitudinal data. Objective data about the relationship between IDDM and long term cognitive functioning is particularly important if recommendations form the Diabetes Control and Complications Trials (DCCT) for stricter control of blood sugar in adults is to be extended to children. Because stricter control brings with it an increased risk for episodes of hypoglycemia, it is crucial to understand how the degree of metabolic control relates to children's long term learning. Information obtained in this study will help nurses and other health and educational professionals provide optimal care and education to families and children with IDDM.