Diabetes II and cancer are interconnected, and the study reaffirms that.

Researchers in Sweden and China have identified a protein in the blood they believe can pose as an early warning sign for patients at risk of diabetes or fatal cancer.

The researchers took into account 20 years worth of health records for more than 4,500 middle-aged adults on the Malmo diet and cancer study. According to their analysis, those who had the highest level of prostasin, which is a protein that circulates in the blood, had almost a double risk of developing diabetes in comparison with those with the lowest levels.

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Some participants already enrolled in the study had diabetes - so, the scientists looked at participants who did not have the disease that went to be diagnosed later on in their lifetime. The study showed that people holding prostasin levels in the top 25% were 76% more likely to develop diabetes than those in the bottom quarter.

Dr Xue Bao, who is the first author of the study at the Affiliated Hospital of China's Nanjing University medical school, explained that prostasin was a potential new risk factor for diabetes and death from cancer, especially for people who have high blood sugar.

Prostasin has a number of roles in the body, as it is responsible for regulating blood pressure and blood volume, as well as the suppression of growth of tumors fuelled by high blood sugar. Although science already knows that type 2 diabetes is known to raise the risk of certain cancers, such as pancreatic, liver, bowel and endometrial tumors, the biological mechanisms backing this are not clear.

After the link between prostasin and diabetes was researched, scientists started looking into whether high levels of prostasin predicted greater cancer risk.

Those in the top 25% of prostasin levels were 43% more likely to die from cancer compared to those in the bottom quarter.

The paper was published in Diabetologia.

According to the study, those holding higher levels of prostasin and blood sugar were at significantly higher risk of death from cancer. For every doubling in the concentration of the protein, the risk of death by cancer rose 24% in those without high blood sugar, and 139% in those with high blood sugar.

“Particular attention should be paid to these individuals,” the authors write.

Is prostasin part of the disease, or is it just a biological marker that exacerbates conditions as they develop? It is not entirely clear; however, the authors suggest the possibility that prostasin levels rise when attempting to suppress blood sugar levels, but are not able to stop or reverse the damage caused by that.

“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 in Sweden.

“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.”

Jessica Brown from 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.”