Men and women with diabetes are at increased risk for developing cancer of the colon and rectum, according to a report from Sweden.

The findings are based on an analysis of data pooled from 15 studies, which included more than 2.5 million subjects. Most, but not all, studies have shown a link between diabetes and colon cancer, but some inconsistencies were present, including whether the association was seen in both men and women.

Dr. Susanna C. Larsson, from the Karolinska Institute in Stockholm, and colleagues found that diabetes increased the risk of colorectal cancer by 30 percent. The results were similar in US and European studies, the investigators report in the Journal of the National Cancer Institute.

Further analysis failed to uncover a significant difference between men and women. Likewise, diabetes raised the risk of colon and rectal cancers to a similar extent, by 43 percent and 33 percent, respectively.

“These findings provide evidence for a role of hyperinsulinemia or factors related to insulin resistance in colorectal carcinogenesis,” the researchers conclude.

“Our results,” they add, “have important clinical and public health implications,” especially in light of the increase in diabetes that is expected with the growing obesity epidemic in the US and elsewhere.

SOURCE: Journal of the National Cancer Institute, November 16, 2005.