Oral cancer in Taiwan: is diabetes a risk factor?

The association between diabetes and oral cancer is rarely studied. We investigated the trends of oral cancer in the Taiwanese general population and the possible link with diabetes. The trend of age-standardized oral cancer incidence in 1979-2007 in Taiwan was calculated from the Taiwan Cancer Registry database. A total of 494,817 men and 503,723 women without oral cancer from a random sample of 1,000,000 individuals covered by the National Health Insurance were followed up from 2003 to 2005. Cox regression evaluated the adjusted relative risk considering potential detection bias and covariates. The trends increased significantly in both sexes. Diabetic patients had a higher chance of oral cancer detection because they more frequently visited related medical professionals. Although diabetes status and duration were significantly associated with oral cancer in unadjusted models, none was significant after multivariable adjustment. For comorbidities, chronic obstructive pulmonary disease (a surrogate for smoking) and alcohol-related diagnoses were significant for men, and hypertension and alcohol-related diagnoses were significant for women. Additionally, angiotensin-converting enzyme inhibitors/angiotensin receptor blockers and insulin were significant with relative risk (95 % confidence interval) of 1.642 (1.174-2.295) and 2.136 (1.003-4.547), respectively, in men. Oral cancer is increasing in Taiwan. Diabetes is not a risk factor after multivariable adjustment. The increasing trend of oral cancer may not be ascribed to diabetes. The association between oral cancer and some comorbidities and medications requires confirmation and may provide strategies for the prevention of oral cancer.