Diabetes, or even high blood sugar levels that can lead to diabetes, appear to raise the risk of several major cancers, according to a large Korean study.

In previous studies, diabetes has been consistently linked to cancers of the pancreas, liver and colon/rectum, the researchers note, but the link with other types of cancer has been less clear.

Dr. Sun Ha Jee, from Yonsei University in Seoul, and colleagues conducted a 10-year forward-looking study involving more than 1 million Koreans ranging in age from 30 and 95 years who had a medical evaluation between 1992 and 1995.

During follow-up, men and women with high fasting blood glucose levels were about 25 percent more likely to die from cancer than those with normal or low levels, the investigators report in the Journal of the American Medical Association.

High glucose levels were most strongly linked to pancreatic cancer for both men and women. Other malignancies linked to high glucose levels included cancer of the esophagus, liver, and colon/rectum in men, and liver and cervix in women.

“While the generalizability of the findings is uncertain, we have shown that fasting serum glucose level and diabetes are associated with cancer risk in a population far leaner than the Western populations in other studies,” the investigators note.

Since most of the Korean population is relatively lean, taking obesity out of the equation, the findings suggest that excessive insulin levels triggered in response to decreased insulin sensitivity may be the underlying cause of the increased cancer risk.

In a related editorial, Dr. Kathleen A. Cooney and Dr. Stephen B. Gruber, from the University of Michigan Medical School in Ann Arbor, comment: “As diabetes becomes an increasing public health concern in modern societies, the cancer risks looming on the horizon are now being recognized. Strategies to address the emerging epidemics of diabetes and obesity are likely to have a broad impact on public health.”

SOURCE: Journal of the American Medical Association, January 12, 2005.