However, researchers at the University of Bath say that many years of work are needed before any treatment could be produced.

Type I diabetics - most of whom develop an extreme form of the illness while they are young - lack a certain type of pancreatic cells.

This is the first step in the development of what could ultimately provide a cure for people suffering from diabetes - but there is a lot more work to do Professor Jonathan Slack, University of Bath

These produce insulin, which helps them control blood sugar levels, and without regular injections of the hormone, these diabetics could die.

Until recently, it had been believed that these pancreatic cells were irreplaceable, but a number of research projects are aiming to produce a new supply.

The Bath scientists believe that another organ close to the pancreas, the liver, could be the solution.

Although the liver has a completely different function - removing toxins such as alcohol from the body - their origins in the very young foetus are very similar.

Common source

Although they developed from very similar "stem" cells, at a certain point in the pregnancy, some of them developed into liver cells, and some began forming the pancreas.

The scientists wondered if, with the right help, that process could be reversed.

Previous studies had revealed a gene believed to be important in pancreas cell development, and the team, led by Professor Jonathan Slack, injected a "super-active" form of it into both human liver cells in the laboratory, and liver cells from frog tadpoles.

They found that the tadpole liver cells began behaving like pancreatic cells, with some of them producing insulin.

The human cells also changed character, again with some of them making insulin.

Cure hope

Professor Slack suggested that there was plenty of "spare capacity" in the liver that could be harnessed to make replacement insulin-producing cells.

This is a very important piece of research Professor Kevin Docherty, University of Aberdeen

In theory, if a way could be found to deliver the super-active gene safely into the liver - and this is no mean feat - then an effective treatment, and perhaps even a cure, for diabetes might be only an injection away.

Professor Slack said: "The results from these experiments have been very encouraging.

"This is the first step in the development of what could ultimately provide a cure for people suffering from diabetes - but there is a lot more work to do."

Next steps involve moving the experiments to live adult mammals to see if the technique works there.

Professor Kevin Docherty, from the University of Aberdeen, suggested that even if an injection to cure diabetes did not materialise, the Bath research could be very helpful in other ways.

He said: "This is a very important piece of research.

"It could help us make enough insulin-producing cells in the laboratory to then transplant into the patient."