Researchers say they have discovered how a high-fat Western-style diet may increase the risk of type 2 diabetes.
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 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.