The pathogenesis of the periodontal disease is complex, because it derives from the initiation and maintenance of the chronic inflammatory process by the plenty microbial flora and its numerous bacterial products. The purpose of our study was to make evidence of the histopathological changes occurring in the gingival epithelium in patients with both diabetes mellitus and periodontal disease. METHODS Our study was carried out on gingival tissue from 68 diabetic patients with specific symptoms of periodontitis. The preparations were processed by Hematoxylin-Eosin staining technique and trichromic staining after the Goldner-Szekely method. RESULTS Although non-specific, since they have been generally found in chronic gingival inflammation, the noticed changes were significant and some of them had specific aspects for the diabetic patients: gingival epithelium changes like acanthosis type; the presence of inflammatory cells such as polymorphonuclear leukocytes and/or lymphocytes among the cells of the stratified squamous epithelium; surface ulceration areas covered by hematic and fibrino-leukocytary detritus; the epitheliocytes keratinization in the superficial layers. CONCLUSIONS The diabetic patients with periodontitis frequently associate hypertrophy changes of the gingival epithelium with the epithelial permeability alteration and the presence of the intraepithelial inflammatory cells, subsequently leading to degenerative lesions and epithelial ulceration.