Ninety-seven diabetic patients who had taken insulin for 50 yr and longer were surveyed by questionnaire to identify factors that might explain their unusual longevity. The analysis suggested that the long survival of this group was related to the following: maintenance of normal or near normal body weight, regular contact with a personal physician, periodic blood glucose determinations, frequent urine testing, regular exercise, and longevity of the parents and grandparents. The results support the conclusion that careful management of diabetes favors longevity.