The incidence of autoimmune hemolytic anemia (AIHA) is highest among the elderly, and thus it is frequently associated with co-morbidities such as diabetes mellitus (DM). However, there have been few reports on the impact of these co-morbidities on survival in patients with AIHA. Therefore, we retrospectively reviewed the records of 53 consecutive AIHA patients and assessed the impact of DM on survival. Eighteen of the 53 patients had DM. The estimated 4-year overall survival (4y-OS) for all patients was 84.9%. Infection was the most frequent cause of death, and fatal infections were exclusively observed in patients with DM. The deaths in DM patients occurred frequently within 1 year, to give significantly poor survival (4y-OS; 69.3% versus 93.6%, P=0.0064). The presence of DM was identified as the only significant risk factor for survival. A large prospective investigation is warranted to assess the impact of co-morbidities on survival in patients with AIHA.