OBJECTIVE -Numerous publications have already demonstrated that diabetes is a risk factor for the development of periodontal diseases and various inflammatory lesions in the oral mucosa. A possible correlation between diabetes and oral premalignancies and tumors was examined in this study, as no literature data are available concerning this problem.RESEARCH DESIGN AND METHODS -Stomato-oncological screening was carried out on 200 diabetic patients in the medical departments; the control group included 280 adult dentistry outpatients. The lesions found were classified into three groups: inflammatory lesions, benign tumors, and precancerous lesions. A retrospective diabetes screening of 610 inpatients with histologically confirmed oral malignancies was also performed. The control group comprised 574 complaint-and tumor-free adults. Fasting blood glucose levels were determined in both groups, and the tumor location was registered in the cancer patients.RESULTS -Benign tumors were found in 14.5% and precancerous lesions in 8% of diabetic patients. In the control group these values were significantly lower, at 6.4 and 3.2%, respectively (P Ͼ 0.01). Earlier Hungarian screening studies indicated similar frequency of these lesions in the general population. The proportion of oral cavity lesions was higher among diabetic patients compared with that of the control patients. In the oral cancer patient group, diabetes was present in 14.6% and an elevated blood glucose level in 9.7%. These values are significantly higher than those for the tumor-free control group (P Ͻ 0.01). The gingival and labial tumor location was significantly more frequent among diabetic cancer patients than in the nondiabetic group (P Ͻ 0.01). The combination of diabetes and smoking means a higher risk for oral precancerous lesions and malignancies.CONCLUSIONS -Diabetes may be a risk factor for oral premalignancies and tumors. Diabetes Care 27:770 -774, 2004C orrelations between diabetes and inflammatory oral lesions were first published in the 19th century (1). Gingivitis and destructive periodontitis with a rapid loss of the teeth were described as cardinal, pathognomic symptoms of diabetes (2,3).The discovery of insulin treatment justified a close correlation between the disorder of the carbohydrate metabolism and oral inflammatory complications (4). The adequate treatment of diabetes results in marked improvement of the gingival and periodontal lesions.Diabetes patients have further inflammatory complications of the oral mucosa. The decreased rate of saliva secretion and the low pH value result in chronic cheilitis and glossitis with progressive atrophy of the covering epithelial layer (5).The inflammation-mediated carcinogenesis is a well-known empirical fact, but the exact pathway of this transition has not been perfectly clarified until now (6 -9). Is there any correlation between diabetes and tumor genesis of the oral cavity? Surprisingly, there are no literature data concerning this problem. Accordingly, in the present study, we have attempted...