Coronavirus may be triggering diabetes in previously healthy people, a team of international experts fear.

New cases of the blood sugar condition have been repeatedly diagnosed in patients who have tested positive for Covid-19, the group of 17 leading clinicians say in an open letter published on Friday.

They admit it remains unclear how the two may be interlinked.

Research has previously shown that ACE-2 - the protein the coronavirus appears to bind to with in the human body - is not only located in the lungs but also in organs involved in glucose metabolism including the pancreas, small intestine, liver and kidney.

Scientists hypothesise that, if the virus attaches to these organs, it may then cause multiple dysfunctions of glucose metobolism leading to onset-diabetes in some cases.

A global registry of new cases of diabetes in patients with Covid-19 - named the CoviDiab Registry Project - has now been created, the experts say in their letter to the New England Journal of Medicine

Francesco Rubino, professor of metabolic surgery at King's College London and co-lead on the registry, said: "We are of course trying to understand what situation is behind the observations."

Previous evidence has already suggested that coronavirus can cause more severe complications in patients with pre-existing diabetes: roughly a quarter of people who have died with Covid-19 have been reported to have diabetes.

Prof Rubino said: "Diabetes is one of the most prevalent chronic diseases and we are now realising the consequences of the inevitable clash between two pandemics.

"Given the short period of human contact with this new coronavirus, the exact mechanism by which the virus influences glucose metabolism is still unclear and we don't know whether the acute manifestation of diabetes in these patients represent classic type 1, type 2 or possibly a new form of diabetes."

But some experts urged caution over the perceived correlation.

Dr Riyaz Patel, associate professor of cardiology at University College London Hospital, said he was wary of what was currently only observational evidence of a link.

He said: "The data may be confounded for a few reasons. For example we know that any stress inducing illness can cause blood sugar levels to temporarily rise and we see this for example with heart attacks."

And he added: "Also, people who are more likely to get very sick with Covid may be at risk of developing diabetes anyway perhaps because they are overweight."