"People with diabetes have a two- to threefold higher risk for hepatocellular carcinoma compared with those without diabetes," said V. Wendy Setiawan, Ph.D., assistant professor in the Department of Preventive Medicine at Keck School of Medicine of the University of Southern California. "We also found that the interethnic differences in the prevalence of diabetes were consistent with the pattern of hepatocellular carcinoma incidence observed across ethnicities: Ethnic groups with a high prevalence of diabetes also have high hepatocellular carcinoma rates, and those with a lower prevalence of diabetes have lower hepatocellular carcinoma rates."

The number of new cases of hepatocellular carcinoma in the United States tripled in the past three decades, with Latinos and African-Americans experiencing the largest increase in incidence. Prior research has suggested that diabetes may be a risk factor for hepatocellular carcinoma, and its increasing incidence may be contributing to the rising rate of hepatocellular carcinoma.

"People with diabetes should be aware that their condition is associated with a higher risk of developing hepatocellular carcinoma," Setiawan said. "Maintaining a healthy weight, managing their diabetes, preventing and treating hepatitis infection, and limiting alcohol and tobacco use should be in their priority to-do list."

In addition, Setiawan said that public health efforts encouraging obesity/diabetes prevention and effective diabetes management should be directed at high-risk populations.

Setiawan and colleagues examined if the association between diabetes and hepatocellular carcinoma differed by race/ethnic group. They analyzed data from more than 150,000 people enrolled in the Multiethnic Cohort Study between 1993 and 1996. During the study follow-up period of about 15 years, 506 cases of hepatocellular carcinoma were reported: 59 cases in non-Hispanic whites, 81 in African-Americans, 33 in Hawaiians, 158 in Japanese-Americans, and 175 in Latinos.

Compared with non-Hispanic whites, Latinos had 2.77 times the risk for being diagnosed with hepatocellular carcinoma, the highest risk identified. Native Hawaiians had 2.48 times the risk; African-Americans, 2.16; and Japanese-Americans, 2.07.

The prevalence of diabetes was consistent with that of hepatocellular carcinoma. Sixteen percent of Hawaiians, 15 percent of Latinos and African-Americans, 10 percent of Japanese-Americans, and 6 percent of non-Hispanic whites had diabetes. Compared with those without diabetes, Latinos with diabetes had 3.3-fold higher risk for hepatocellular carcinoma; Hawaiians, 2.33-fold higher risk; Japanese-Americans, 2.02-fold higher risk; African-Americans, 2.02-fold higher risk; and non-Hispanic whites had 2.17-fold higher risk.

Hepatocellular carcinoma was attributed to diabetes in 26 percent of cases in Latinos, 20 percent of Hawaiians, 13 percent of African-Americans, 12 percent of Japanese-Americans, and 6 percent of non-Hispanic whites, the researchers estimated. According to Setiawan, eliminating diabetes could potentially reduce hepatocellular carcinoma incidence in all racial/ethnic groups, with the largest potential reduction possible in Latinos.