We prospectively investigated 615,532 diabetic patients and 614,871 age-matched and sex-matched control subjects selected from National Health Insurance claims for malignant neoplasms of liver and biliary tract (International Statistical Classification of Diseases and Related Health Problems, 9th edition, codes 155 and 156, respectively) between 2000 and 2006. The person-year approach with Poisson assumption was used to estimate the hazard rates. We also evaluated the age-specific and sex-specific relative risks of these two malignancies in relation to diabetes with Cox proportional hazard regression model with adjustment for potential confounders. The overall hazard rate of malignant neoplasm of the liver was 32.76 and 17.41 per 10,000 patient-years, respectively, for diabetic men and women; the corresponding figures for biliary tract neoplasm were much lower at 1.42 and 1.60 per 10,000 patient-years. Compared with control subjects, diabetic patients had a two-fold increased risk of malignant neoplasm of the liver, but this risk was attenuated by adjusting for selected clinical risk factors (hazard ratio [HR] 1.21; 95% confidence interval [CI] 1.17-1.25). Additionally, diabetic patients were associated with increased risk of biliary neoplasms with an approximate magnitude of 20%-30%, but the HR was attenuated and became insignificant after adjustment for clinical risk factors (HR 1.07; 95% CI 0.95-1.21). Diabetic patients with cirrhosis had the highest relative risk of liver neoplasm (HR 85.25; 95% CI 76.84-94.58), whereas those with cholangitis had the highest risk of biliary tract neoplasm (HR 70.30; 95% CI 51.95-95.12) compared with control subjects without any clinical risk factors.
Conclusion: This population-based study confirms the association of diabetes with liver neoplasm and suggests that diabetic patients with certain clinical risk factors should be educated for strict adherence of liver neoplasm screening.