Our study evaluates the correlation between dental and diabetes locus of control beliefs and the potentiality of locus of control beliefs in predicting oral health behavior, dental status, diabetes compliance, and HbA1c level by using situation-specific locus of control scales and considering the value dimension. Data were collected by means of a quantitative questionnaire, a clinical oral examination and patient records. The research population comprised 149 insulin-dependent diabetics who had teeth of their own. Variables were the frequencies of tooth brushing and dental visiting, oral indexes, diabetes adherence, and HbA1c level. Dental and diabetes locus of control beliefs correlated with each other. Dental locus of control associated with frequency of dental visiting, plaque index, decayed surfaces, and with root caries, but diabetes locus of control associated only weakly with adherence with diabetes self-care regimens and not at all with HbA1c level. Correlations between dental locus of control and oral indexes were stronger among those having high value for dental care. Although there were correlations between dental and diabetes locus of control beliefs, only dental locus of control beliefs are practicable for determining health behavior and health status. It is therefore concluded that locus of control beliefs are health behavior specific.