Objective: Due to difficult identification of pathologic conditions of oral mucosa in diabetic patients, the aim of the study was to evaluate gingival epithelial cells by exfoliative cytology in patients with type 2 DM and periodontal disease before and after periodontal therapy. Methods: The group I (100 patients with periodontal disease and type 2 DM) and the group II (100 patients with periodontal disease) participated in the study. Oral examination was done, the gingival smears taken and periodontal therapy applied. Seven days afterwards, smears were taken again and the cytomorphometric analysis was done. Results: Cytomorphometric values were higher in the group I before and after therapy. Conclusion: Noteworthy differences in the cytomorphology of the gingiva found in patients with DM type 2 comparing to systemically healthy patients decreased after periodontal therapy. Changes are not specific for DM and further studies are needed to determine the predictive value of cytomorphometric analysis.