Diabetics May Face Higher Risk of Colon Cancer

Women with diabetes are 50 percent more likely to suffer from colorectal cancer than those who do not have the metabolic disorder, according to a study by School of Public Health researchers.

"Colorectal cancer and type 2 diabetes share a number of common factors, including obesity, so it is interesting to see the direct line between these two conditions," says lead investigator and SPH assistant professor Andrew Flood. The researchers followed 45,000 women with no history of colorectal cancer or diabetes from 1987 to 1989 and from 1995 to 1998 to examine the association between the two conditions.

Flood says it is unknown why diabetics have a higher risk of colorectal cancer. But one possibility is that the risk may be related to the elevated concentration of insulin typically seen in type 2 diabetes patients.

"In the early stages of the disease, people become insulin resistant, meaning they must produce more and more insulin to regulate their blood sugar," Flood says. "Even after frank diabetes begins, insulin levels remain chronically elevated for extended periods before the pancreas can no longer supply the level of insulin the body demands."

The team found no elevated risk of colorectal cancer in pre-diabetic women. The researchers believe this may have something to do with the length of time and the degree of elevated insulin in the body.

Flood says the best way women with diabetes can reduce their risk of colorectal cancer is through management of blood sugar.

• Listen to a Public Health Moment about this study