A new study shows how and why a high-fat diet and obesity are linked to type 2 diabetes.

Researchers at the University of California, San Diego have found a molecular connection between the high-fat Western-style diet and the disruption of insulin production. A single enzyme, called GnT-4a, enables the beta cells in the pancreas to sense blood glucose levels and produce the appropriate amount of insulin.

Studies with mice show that this enzyme is suppressed by a high-fat diet, resulting in diabetes, the researchers said.

The study appears in the Dec. 29 issue of the journal Cell.

Early in the disease, diabetes patients produce insufficient insulin that results in hyperglycemia, or elevated blood glucose. Beta cells overcompensate and produce too much insulin, resulting in full-blown type 2 diabetes. More than 200 million people worldwide have been diagnosed with the disease, 20 million in the United States alone.

"In fact, the likelihood that obesity will lead to diabetes is so common that this epidemic is sometimes referred to as 'diabesity,' " Jamey Marth, a professor of cellular and molecular medicine at UCSD and an investigator with the Howard Hughes Medical Institute, said in a prepared statement.

High levels of insulin have also been implicated in contributing to other diseases such as cancer, cardiovascular disease and stroke. The researchers said new forms of treatment may include inhibiting the GnT-4a gene to reduce insulin production.