Research on treatment for diabetes and co-occurring eating disorders is sparse. We examined outcomes from multidisciplinary residential treatment for women with type 1 diabetes and eating disorders and the impact of treatment duration on outcomes. Participants were 29 women with type 1 diabetes and eating disorders receiving residential treatment. Repeated measures analyses of variance examined changes in blood glucose and psychological symptoms over treatment. Analyses were repeated to include treatment by duration interactions. Treatment produced significant reductions in blood glucose, eating disorder symptoms, and psychological concerns. Longer treatment duration was associated with greater improvements in psychological symptoms.