A new study published in the Journal of Gastroenterology assessed overall and cause-specific mortality risk during follow-up of Japanese type-2 diabetes mellitus (T2D) patients. This was a longitudinal, multicenter cohort study including 5642 Japanese T2D patients who visited OPDs of nine hospitals, in the year 2013. Among these, 3,999 patients were followed up for an average of 4.5 years. The findings revealed that all-cancer mortality was significantly higher in T2D patients than in the general population. Meanwhile, among malignancies, hepatocellular carcinoma (HCC) conferred the highest mortality risk in T2D patients, even after adjusting for high positivity rates of hepatitis B surface antigen and anti-hepatitis C virus. In T2D patients with platelet counts < 200 × 103/μl, standardized mortality ratios (SMR) of HCC increased from 3.57 to 6.58. On the other hand, T2D patients with platelet count > 200 × 103/μl showed no increase in mortality risk of HCC. The results indicated that HCC-associated mortality risk was the highest among all cancers in Japanese T2D patients. It was stated that regular follow-up may be important for T2D patients with platelet counts < 200 × 103/μl for an early detection of HCC.