The eating disorders anorexia nervosa and bulimia nervosa have been reported to occur in Type I diabetes mellitus. Although prevalence estimates vary, the most rigorous studies yield rates similar to the population at large. Intentional insulin omission is more common, especially in young diabetic women, and at times may indicate an eating disorder in Type I diabetic patients. Both diagnosable eating disorders and intentional insulin omission are associated with worse glycemic control and higher rates of secondary diabetic complications. Recognition of these conditions, followed by carefully coordinated treatment involving both diabetes care providers and mental health providers, is necessary to improve treatment outcome.