Colon Cancer Colon Cancer Basics

New Downside to Diabetes: Colorectal Cancer

If you have diabetes, you may already know you are at increased risk of eye problems, kidney disease, heart disease, stroke and nerve problems. But you may have a new reason to control your blood sugar levels: colorectal cancer.

In a 2004 study, published in the journal Cancer Epidemiology, Biomarkers and Prevention, research suggests that people with diabetes are three times more likely to develop colorectal cancer. European study researchers followed 9,605 people 45 to 70 years old for six years. They found that those with the highest level of a marker for blood sugar levels were at highest risk. Even people with blood sugar levels that were elevated but not high enough to have diabetes—many of whom would be classified as having prediabetes—were at increased risk of colorectal cancer.

Lead investigator Dr. Kay-Tee Khaw, of the University of Cambridge in England, explained that colorectal cancer is not considered a cause or consequence of diabetes, but that high blood sugar levels may play a role in the development of both type 2 diabetes and colorectal cancer.

"We believe raised glucose (blood sugar) levels may simply be a marker of other processes that may influence cancer risk," Khaw said. High blood sugar levels can lead to hyperinsulinemia, a condition in which too much insulin is produced. Insulin and insulin growth factors are involved in cell growth regulation, particularly the growth of certain colon cells.

"We don’t think that there is currently enough evidence to justify increased colorectal screening in people with diabetes," said Khaw, who added that the association between colorectal cancer and high blood sugar levels she observed needs to be confirmed by additional studies.

Making lifestyle factors such as eating a fiber-rich diet, exercising and maintaining a healthy weight, however, are known reduce risk of both colorectal cancer and diabetes. So by eating healthfully and getting fit, people can lower their risk of two of the major chronic diseases linked to aging.