BackgroundThe role of a patient’s functional health literacy (HL) has received much attention in the context of diabetes education, but researchers have not fully investigated the roles of communicative and critical HL, especially in primary care. Communicative HL is the skill to extract health information and derive meaning from different forms of communication, and to apply this information to changing circumstances. Critical HL allows the patient to critically analyze information and to use this information to achieve greater control over life events and situations. We examined how HL, particularly communicative and critical HL, is related to the patient’s understanding of diabetes care and self-efficacy for diabetes management in primary care settings. We also examined the impact of patient–physician communication factors on these outcomes, taking HL into account.MethodsWe conducted a cross-sectional observational study of 326 patients with type 2 diabetes who were seen at 17 primary care clinics in Japan. The patients completed a self-administered questionnaire that assessed their HL (functional, communicative, and critical), understanding of diabetes care, and self-efficacy for diabetes management. We also examined the perceived clarity of the physician’s explanation to assess patient–physician communication. Multivariate regression analyses were performed to determine whether HL and patient–physician communication were associated with understanding of diabetes care and self-efficacy.ResultsA total of 269 questionnaires were analyzed. Communicative and critical HL were positively associated with understanding of diabetes care (β = 0.558, 0.451, p < 0.001) and self-efficacy (β = 0.365, 0.369, p < 0.001), respectively. The clarity of physician’s explanation was associated with understanding of diabetes care (β = 0.272, p < 0.001) and self-efficacy (β = 0.255, p < 0.001). In multivariate regression models, HL and perceived clarity of the physician’s explanation were independently associated with understanding of diabetes care and self-efficacy.ConclusionsCommunicative and critical HL and clear patient–physician communication were independently associated with the patient’s understanding of diabetes care and self-efficacy. The potential impact of communicative and critical HL should be considered in communications with, and the education of, patients with diabetes in primary care settings.