Cancer risk may rise before and immediately after a diabetes diagnosis

A new study indicates that individuals with diabetes may have an elevated risk of developing cancer before and immediately after a diabetes diagnosis. Published early online in Cancer, a peer-reviewed journal of the American Cancer Society, the findings point to the need for a better understanding of the link between diabetes and cancer.

Studies suggest that type 2 diabetes may increase the risk of developing several different types of cancer. The highest risk appears to be shortly after a diabetes diagnosis, which suggests that the higher rates of cancer among diabetics may, in part, reflect their increased contact with health care providers, allowing for more testing.

To further evaluate the temporal relationship between diabetes and cancer, Iliana Lega, MD, MSc, of the University of Toronto, and her colleagues looked at cancer incidence in more than 1 million adults at various time points.

Individuals with diabetes were 1.23-times more likely to have been diagnosed with cancer in the 10 years before a diabetes diagnosis compared with individuals without diabetes. "This supports existing hypotheses that shared risk factors may be contributing to both cancer and diabetes diagnoses," said Dr. Lega.

Cancer incidence was also significantly higher in persons with diabetes within the first three months after diagnosis, but not after this time period. "This may in part be explained by increased health care visits and screening tests following a diagnosis of diabetes," Dr. Lega explained.

Dr. Lega notes that the growing epidemic of diabetes may lead to an increased burden of cancer. "There is excellent evidence that diabetes can be prevented and that metabolic changes leading to diabetes can be reversed with lifestyle changes. Similarly, diet and exercise interventions have also been shown to reduce cancer risk and improve cancer outcomes in the general population," she said. "Our findings are important because they underscore the need for further research that examines the impact of exercise and healthy diet on cancer risk specifically in patients with or at risk for diabetes.