Although some studies have suggested a bidirectional relationship between diabetes and periodontal disease, there were no appropriate tools for nurses to evaluate oral status and oral health behaviors in patients with diabetes. Therefore, the Diabetes Oral Health Assessment Tool (DiO-HAT©) was developed with items contributed by health care professionals (diabetologists, periodontal specialists, a preventive dentist, a Certified Nurse in Diabetes Nursing, a national registered dietitian, registered nurses, a dental hygienist, and nursing researchers) who were involved in the medical care of patients with diabetes. Subsequently, a survey of 700 Diabetes Nurse Specialists (DNS) was conducted to determine their score of recognition and implementation of the DiOHAT©, however, 304 participants (43.4%) responded. Constructive concept validation and the Cronbach's alpha coefficient for all assessment items was 0.932, indicating high reliability: Factor 1, Patient's oral health status (α = 0.874); Factor 2, Implementation of oral health behaviors (α = 0.890); Factor 3, Information transmission regarding dental visits (α = 0.862); and Factor 4, Perceptions and knowledge of oral health behaviors (α = 0.793). Although the mean score of recognition of DiOHAT© was 3.5 ± 0.4 points, the mean value of the implementation score was 1.5 ± 0.5 Y. Kuwamura et al. 1711 points (obtained using a 4-grade scale). The implementation scores were significantly lower than the recognition scores for all items (p < 0.001). The findings suggested that the DNS were not inclined to implement all items of DiOHAT©, despite recognizing their importance.