In the past decade, research has increasingly discovered the relevance of depressive symptoms for the development and course of diabetes, particularly in diabetes type 2. The present paper provides an update on the present state of empirical research concerning this question.One fourth of all patients with diabetes mellitus suffer from depressive symptoms up to and including states of depressive disorders. The studies reviewed advise that depression in patients with diabetes concur with an unfavourable attitude towards the illness as well as towards treatment, a reduction in quality of life, an increased risk for the development of follow-up diseases as well as an increase in mortality risk. As a cause for the increasing risk in morbidity and mortality in depressive patients with diabetes, both neuroendocrinologic changes as well as unfavourable therapy and illness attitudes are discussed. First studies document that psychotherapeutic interventions are helpful in increasing the quality of life of depressive patients with diabetes and improving therapy behaviour.