Previous studies have shown a high incidence (77%) of isolation of Candida spp. from the oral cavities of patients with type 1 diabetes mellitus. The aim of the present study was to assess the prevalence of yeast in the oral cavities of patients suffering from type 1 and type 2 diabetes mellitus. The patients were classified according to the level of diabetic control (HbA1c), and further stratified on the presence or absence of dental prosthesis. Oral rinse samples were assessed for the growth of yeast and the degree of colonization. Oral isolates were defined to the species level by both phenotypic and novel molecular methods. The overall proportion (60%) of diabetic patients who had Candida spp. isolated from the oral cavity was similar to that previously reported. Local oral factors, such as the presence of dentures, seemed to have a greater influence than diabetic status on the amount and species of Candida isolated from the oral cavities of diabetic patients. Diabetic patients with dentures had more non-albicans Candida isolated from their mouths than dentate diabetic patients. Candida dubliniensis was isolated from diabetic patients and may have a predilection for dentate patients.