Of the 25,672 patients who visited this clinic between January 1964 and March 1973, 126 were diabetic. These were examined statistically and the following results were obtained. 1. Together with diabetes the following disorders pertaining to the realm of oral surgery were observed: Alveolar pyorrhea (49 cases), infection of oral tissues other than periodontal tissues (24 cases), simple periodontitis (15 cases), tumors (13 case), dental caries (9 cases), neuralgia (6 cases) and several disorders. 2. Of these 126 cases, 85 needed tooth extraction, which was actually performed in 67 cases, with the following results: (a) Of the 67 cases, 13 developed complications such as dry socket, postoperative infection, sequestrum around the extraction socket, etc. This was a significantly higher incidence than in an equal number of controls. (b) In the cases with complications convalescence was prolonged to an average of 54.2 days. (c) In the cases with complications, the preoperative fasting blood sugar level averaged 194.5 mg/di, which was much higher than in the cases which did not develop complications (average 142.4 mg/di).