Narrator: This is Science Today. An elusive link between a high-fat, Western-style diet and the onset of type 2 diabetes, which affects 20 million Americans, has been discovered in mice studies by researchers at the University of California,San Diego. Study leader Dr. Jamey Marth says it's a single gene that encodes an enzyme called GnT-4a, which is key to insulin production.

Marth: We realized very early that mice lacking this gene had very high blood-glucose levels very early in life – even when they were provided a good, healthy diet.

Narrator: In further studies, mice with the gene intact had a disruption in GnT-4a expression when placed on a high-fat diet, leading to type 2 diabetes.

Marth: So if we can make an animal that now will continue to express this enzyme, no matter whether it has a healthy or high-fat diet, and then if we can see as a result of that, that the animal's resistant to type 2 diabetes, then we can say without a doubt, this is the key mechanism that is gone astray. It's very likely that
it's the same mechanism in humans.

Narrator: For Science Today, I'm Larissa Branin.