Previous studies have proposed common psychological factors between oral health behavior and diabetes self-care. The aim here was to describe and analyse more comprehensively the relationships between dental and diabetes health behavior on the basis of attribution theory. The likeness between subjects' own assessments, similarities of the causes given to success and failure, and the predictive power of own dental assessments concerning the metabolic balance of diabetes were studied. The research population was composed of 149 IDDM patients. Data were collected by means of a quantitative questionnaire, a clinical oral examination and from patient records. It was found that from the patients reporting success with avoiding gingivitis 82% also reported success with metabolic status and they also had lower mean HbA1c levels than patients assessing failure with gingivitis. There were some correlations between causes of failure: not bothering to clean approximal surfaces correlated with non-adherence to diabetes treatment instructions, and laziness as the cause of caries correlated with non-adherence to diabetes treatment instructions and with poor motivation for diabetes care. It can be concluded that there are some common determinants for both dental health behavior and diabetes self-care. This connection should be taken into account in health education by health care professionals.