Doctors have identified a protein in the blood they believe could serve as an early warning sign for patients who are at risk of diabetes and death from cancer.
Researchers in Sweden and China analysed two decades of health records from more than 4,500 middle-aged adults on the Malmö diet and cancer study. They found that those with the highest levels of prostasin, a protein that circulates in the blood, were almost twice as likely to have diabetes than those with the lowest levels.
Some of those enrolled on the study already had diabetes, so the scientists looked at who among those without the disease went on to be diagnosed later. People in the top quarter for prostasin levels turned out to be 76% more likely to develop diabetes than those in the bottom quarter.
Dr Xue Bao, the first author on the study at the Affiliated hospital of Nanjing University medical school in China, said prostasin was a potential new “risk marker” for diabetes, but also death from cancer, particularly in people who have high blood sugar.
Prostasin plays several roles in the body, such as regulating blood pressure and blood volume, and it also suppresses the growth of tumours that are fuelled by high blood sugar. While type 2 diabetes is known to raise the risk of certain cancers, including pancreatic, liver, bowel and endometrial tumours, the biological mechanisms are far from clear.
After investigating the link between prostasin and diabetes, the researchers looked at whether people with high levels of the protein were at greater risk from cancer.
Writing in Diabetologia, they describe how those in the top quarter for prostasin levels were 43% more likely to die from cancer than those in the bottom quarter.
Participants with high levels of both prostasin and blood sugar were at significantly higher risk of dying from cancer, according to the study. For every doubling in prostasin concentration, the risk of cancer death rose by 24% in those without high blood sugar, and by 139% in those with high blood sugar. “Particular attention should be paid to these individuals,” the authors write.
It is unclear whether a high prostasin level plays a part in disease or is merely a biological marker that ramps up as the condition develops. One possibility, the authors suggest, is that prostasin levels rise in an attempt to suppress high blood sugar levels, but are not able to stop or reverse the damage caused.
“The relationship between diabetes and cancer is poorly understood and this protein could provide a possible shared link between the two conditions,” said Prof Gunnar Engström, a senior author on the study at Lund University.
“We now need to examine to what extent prostasin is causally related to these diseases or whether it is a valuable marker of increased disease risk,” Engström added.
“It might also be possible to identify individuals with increased risk of diabetes and cancer, and offer preventive measures.”
Because the findings are drawn from people in one city, they may not apply to wider populations. The researchers also point out that prostasin was measured from frozen blood taken at only one time point, and that the study was unable to distinguish between different types of diabetes.
Jessica Brown, at Diabetes UK, said: “We know there is a connection between diabetes and some types of cancer, and this study suggests levels of a particular protein, called prostasin, is linked to both conditions.
“Gaining a better understanding of the changes inside the body that may put people at risk from diabetes and cancer will help scientists find ways to protect people from these serious conditions, but there’s still much to discover.
“We need further research to find out if prostasin is playing a direct role in the development of type 2 diabetes and poorer cancer outcomes in people with high blood sugar levels.”
