For a year from Jan. 1976 to Dec. 1976, the authors have performed the clinical observation in accordance with audiometric test and clinical findings of 43 cases (male 25 : female 18) who were diagnosed of diabetes mellitus in diabetic clinic of our hospital. The results are as follows ; 1) Eight of 43 cases reveal hearing impairment and almostly abrupt drop or descending in hearing types. 2) The incidence of hearing impairment is higher in middle and older age group. 3) Hearing impairment has not related to duration of the disease but blood sugar level and total serum cholesterol level in some extent. 4) The incidence of hearing impairment is higher in cases accompanied by complications such as retinopathy, hypertension, neuropathy etc. 5) In etiology of hearing impairment, multiple factors seem to be concerned.