Type 2 diabetes has been suggested as an independent risk factor for the development of hepatocellular carcinoma (HCC). However, the role of Type 2 diabetes on the development of HCC in the presence of chronic hepatitis B (CHB) remains inconclusive. We conducted this hospital-based case-control study to evaluate the roles of Type 2 diabetes in HCC development in patients with CHB. From January 2004 to December 2008, a total of 6,275 eligible consecutive patients with chronic hepatitis B virus (HBV) infection were recruited. A total of 1,105 of them were patients with HBV-related HCC and 5,170 patients were CHB but without HCC. We used multivariate logistic regression models to investigate the association between Type 2 diabetes and HCC risk. The prevalence of Type 2 diabetes is higher among HCC patients without cirrhosis than among those with cirrhosis (12.1% vs. 6.7%, p 5 0.003). Type 2 diabetes was associated with a significantly high risk of HCC in female patients after adjusting for age, family history of HCC, city of residence, hepatitis B e antigen and cirrhosis with an odds ratio (95% confidence interval, CI) of 1.9 (1.1-3.4). Restricted analyses among female patients without cirrhosis indicated that Type 2 diabetes was strongly associated with HCC risk with adjusted odds ratio (95% CI) of 5.6 (2.2-14.1). In conclusion, Type 2 diabetes is independently associated with the increased risk of HCC in female CHB patients. Female CHB patients with Type 2 diabetes are of a high HCC risk population and should be considered for HCC close surveillance program.Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide, with 55% occurring in China alone. 1,2 In China, nearly 80% of HCC cases have been linked to hepatitis B virus (HBV) infection and approximately 60-90% of these develop in patients with cirrhosis. 3,4 Other potential risk factors, such as diabetes mellitus, alcohol abuse and obesity, may also play a role in the development of HCC. 5 A number of cohort and case-control studies have investigated the relationship between diabetes mellitus and HCC risk. [6][7][8][9][10][11][12][13][14][15] Type 2 diabetes has been suggested as an independent risk factor for the development of HCC. However, the role of Type 2 diabetes in the development of HCC in the presence of chronic hepatitis B (CHB) has not been well documented. First, only a few cohort studies have followed a population with chronic HBV infection. In addition, most of the case-control studies used a normal population or cancers other than HCC as controls, and chronic HBV infection status was not well matched between cases and controls. 16 Second, none of these studies followed a cohort of patients with CHB or matched cirrhosis status between cases and controls with CHB. The majority of HBV-related HCC develops in patients with cirrhosis, 17 in which the prevalence of Type 2 diabetes is higher than in the general population, and in CHB patients without cirrhosis. 18 So, these studies may also inappropriately estimate the role of Type 2...