Diabetes News:

Study: Type 2 Diabetics On Long-Term Insulin Therpay More Likely to Develop Colorectal Cancer

Patients with type 2 diabetes who require long-term insulin therapy are at a significantly increased risk for colorectal cancer, according to a study reported in the October issue of the journal Gastroenterology.

The study, which involved 24,918 diabetics, found that those who received more than three years of insulin therapy have more than three times the risk of developing colorectal cancer than those who did not receive insulin therapy.

Study author Dr. Yu-Xiao Yang, of the University of Pennsylvania School of Medicine's division of gastroenterology, said it is uncertain whether the increased risk comes from the insulin, the severity of the diabetes or both.

"However, we are hopeful that the identification of this group of patients at a significantly higher risk of developing colorectal cancer will lead to more effective cancer prevention efforts," Yang said.

The researchers said patients should not discontinue insulin therapy because of the study findings, but should ask their doctors about the highly effective colorectal cancer screening methods currently available.

If confirmed in additional studies, the researchers said physicians should consider long-term insulin therapy as a marker of elevated colorectal cancer risk.

The researchers also noted that more study is needed to determine whether a more stringent colorectal cancer screening program is needed in this population.

"At this point, we advocate for strict adherence to the existing colorectal cancer screening guidelines in this patient population, as these measures can effectively reduce the risk of developing colorectal cancer," added Yang.

Previous studies have suggested that type 2 diabetes may be independently associated with increased colorectal cancer risk. Excess internal insulin production in type 2 diabetes has been proposed as the main potential reason. However, the effect of externally administered insulin on cancer risk has not been studied in humans.

The American Gastroenterological Association and multiple government agencies and professional societies underscore the importance of colorectal cancer screening for all individuals 50 years of age and older. Currently, there are a number of approved tests that may be used to screen for colorectal cancer, including barium enema, fecal occult blood test, flexible sigmoidoscopy and colonoscopy.

Source: Diabetes Week staff, October 9, 2004