'Link between diabetes and cancer risk firmly established'

That diabetes and cancer are linked has been a prevailing idea, but has never previously been proven. However, a major recent study has established an undeniable conclusion: diabetes increases a person's risk of developing cancer.

The study analyzed data collected by 47 global studies involving almost 20 million people — including the United States, United Kingdom, China, Australia, and Japan — and confirmed that both diabetes type 1 and 2 increase the risk for cancer. It was found that women with diabetes are especially affected; it seems that they are more likely than men to develop malign tumors. The findings were published in the journal, Diabetologia.

The study was led by Dr. Toshiaki Ohkuma, from the George Institute for Global Health at the University of New South Wales in Sydney, Australia. His colleagues were from the University of Oxford in the U.K., and Johns Hopkins University in Baltimore, MD.

It was found that women with diabetes are 27 percent more likely to develop cancer, compared with healthy women. Men with diabetes are 19 percent more likely to develop cancer than healthy men. Additionally, women with diabetes are 6 percent more likely than men with the same diagnosis to develop cancer. Specifically, women with diabetes have an 11 percent higher risk of developing kidney cancer, a 13 percent higher risk of developing oral cancer, a 14 percent higher chance of developing stomach cancer, and a 15 percent higher chance of being diagnosed with leukemia. One exception was liver cancer; men with diabetes have a 12 percent higher risk of developing the disease than women.

It is still poorly understood why diabetes raises vulnerability to cancer. Some researchers have argued that high blood sugar levels may damage a person's DNA, and thus increase their risk of developing cancer.

Regarding the finding that diabetic women are more likely to develop cancer than men, co-author Dr. Sanne Peters speculates that because women generally live with prediabetes conditions for 2 years longer than men, their vulnerability to cancer may be exacerbated. But there may also be underlying reasons. "Historically," says Dr. Peters, "we know that women are often undertreated when they first present with symptoms of diabetes, are less likely to receive intensive care, and are not taking the same levels of medications as men."

"All of these," she continues, "could go some way into explaining why women are at greater risk of developing cancer. But, without more research we can't be certain." She calls for further research to investigate the cause of these sex-specific differences.

"The differences we found are not insignificant and need addressing," Dr. Peters emphasizes.

"The more we look into gender-specific research the more we are discovering that women are not only under treated, they also have very different risk factors for a whole host of diseases, including stroke, heart disease, and now diabetes."