Breakthrough study pinpoints genetic links between diabetes and cancers

Man has blood sugar level checked for diabetes

The genetic variants behind type 2 diabetes could also increase the risk of breast, bowel and pancreatic cancer, a study suggests.

Links between the diseases have long been known, but the role of obesity in fuelling both cancer and diabetes has made it hard to unpick the genetic connections.

Experts say the identification of specific genetic variants could potentially save thousands of lives, by helping to predict, prevent and treat cases of cancer.

More than 5 million people in the UK have type 2 diabetes, and cancer is now the leading cause of death among those with the condition.

The study by the University of Surrey examined the DNA of 36,000 people to see if  genetics could help to explain why some people with type 2 diabetes also get cancer.

Three key types of cancer

It showed how genetic variants, which are differences in sequences of genes, can simultaneously affect multiple health conditions.

The research focused on the three cancer types that people with type 2 diabetes are at higher risk of developing – post-menopausal breast cancer, colorectal (bowel) cancer and pancreatic cancer.

For the first time, two  specific genetic variants were pinpointed as key contributors to people developing both type 2 diabetes and some cancers.

One variant was linked to the risk of developing both breast cancer and type 2 diabetes. The other affected type 2 diabetes and breast, colorectal (bowel), and pancreatic cancer risk.

A further 17 variants which increase the risk of developing type 2 diabetes, and change the body in ways which increase the risk of cancer – such as through higher blood sugar and insulin levels, inflammation and hormonal changes – were also spotted.

The findings of the study, led by Prof Inga Prokopenko, were presented at the Diabetes UK Professional Conference in London.

‘Multitude’ of factors behind diseases

Dr Elizabeth Robertson, the director of research at Diabetes UK, which part-funded the study, said: “Type 2 diabetes and cancers are complex conditions with a multitude of factors increasing people’s likelihood of developing them.

“This research sheds new light on the role that genetically determined factors play in why some people with type 2 diabetes are also at risk of breast, colorectal and pancreatic cancer.

“In time, this could help doctors to identify people earlier who are at risk of both type 2 diabetes and certain cancers, while paving the way to better, more personalised ways to prevent and treat the conditions.”

Experts say a healthy diet and weight are key to reducing the risks of both type two diabetes and cancer. Nine in 10 cases of type 2 diabetes are linked to excess weight and around four in 10 cases of cancer are linked to lifestyle.

Dr Robertson said: “It’s important to remember that people who have genes that are linked to type 2 diabetes and cancers can still take steps to reduce their risk of both conditions, by getting support to manage your weight, eating well, keeping active and not smoking.”

Dr Helen Croker, the assistant director of research and policy at the World Cancer Research Fund (WCRF), which helped fund the study, said: “WCRF is proud to fund this important research which looks at a population of people that is particularly vulnerable to cancer.

“As cancer is now the leading cause of death among people with diabetes, understanding the complex genetic interplay between type 2 diabetes and several cancer types is crucial for driving prevention strategies for this group of people.”

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