Researchers say they have discovered how a high-fat Western-style diet may increase the risk of type 2 diabetes.
A key gene is suppressed
A team at the University of California, San Diego found eating lots of fat blocks production of an enzyme key to the production of the hormone insulin.
The study was carried out on mice, but the researchers hope their findings will lead to new ways to treat and prevent the condition in man.
Details are published in the journal Cell.
The number of people with diabetes has soared to over two million in the UK.
Of these, the vast majority - about 1.7 million - have the type 2 diabetes, which is associated with obesity.
The San Diego team found insulin production can be disrupted by knocking out a single gene which controls production of a key enzyme called GnT-4a.
They then showed that a high-fat diet suppresses activity of the same key gene.
Insufficient levels of the enzyme were found to compromise the ability of beta cells in the pancreas to produce insulin in response to rising levels of glucose in the blood, for instance after a meal.
Failure to control glucose levels eventually leads to full-blown type 2 diabetes.
The researchers suggest people with an inherited predisposition to type 2 diabetes might have variations in the GnT-4a gene.
Their study showed that when a beta cell lacks sufficient levels of GnT-4a it is unable to absorb glucose across its outer membrane in the usual way.
Thus it becomes insensitive to rising levels of the sugar, and fails to secrete insulin in response.
Researcher Dr Jamey Marth said: "If you could somehow stimulate production of this enzyme, you might be able to render animals, and perhaps humans, resistant to high-fat diet-induced diabetes.
"If our findings can be applied to humans, they should give us important insights into how type 2 diabetes may be prevented and treated."
Andrew Hattersley, Professor of Molecular Medicine, Peninsula Medical School, Exeter, told the BBC News website: "Understanding why people who are obese are more likely to develop diabetes is very important and this research describes a new potential link.
"However, it is uncertain if these mouse models are directly applicable to man.
"In man there is a complex interaction between genetic susceptibility and environmental influence in type 2 diabetes and it is likely that there will be considerable variation in the causes of type 2 diabetes throughout the world.
"A direct role in the genetic predisposition to diabetes in man is speculative."
A spokesman for the charity Diabetes UK said: "This is certainly a very interesting piece of research.
"One thing we do know is that the main factor driving type 2 diabetes is lifestyle; diet and lack of exercise.
"If we could pinpoint what's behind the diet element that would be a significant breakthrough."