In a study of school-age children with new-onset insulin-dependent diabetes mellitus (IDDM), life stress, metabolic control (glycosylated hemoglobin), and psychiatric and psychosocial variables were assessed repeatedly for up to 6 years. Life stress was defined as the number of undesirable life events and extent of life change necessitated by all life events. In univariate longitudinal analyses, total life change units were related to metabolic control, with a trend for number of undesirable events to be associated with metabolic control. In multivariate analyses, metabolic control was related to life change units, whether the glycosylated hemoglobin was in the 1st year of IDDM, IDDM duration, and the diagnosis of pervasive noncompliance with medical regimen. The relationship of life stress to metabolic control among youths with diabetes in significant but clinically modest and may be partially mediated by serious noncompliance with the medical regimen.