The evidence suggests that poor diabetic control in adolescence is often associated with omissions of insulin, overeating and other failures in adherence to the treatment regime in the context of some kind of emotional disturbance. Six young patients with diabetes mellitus and an eating disorder (anorexia nervosa or bulimia), who failed to control their diabetes in order to lose weight and to compensate for bulimic episodes, are discussed. Other noteworthy features were their feelings of hopelessness and their unco-operativeness with treatment. Our knowledge of the pathogenesis of anorexia nervosa and of the special problems faced by diabetic adolescents would lead to a prediction that a combination of the two disorders should arise more often than could be accounted for by chance.