July 20, 2005

Molecular Link Between Obesity and Diabetes Found

LONDON -- Scientists have discovered a molecular link between obesity and type 2 diabetes that could be a potential target for new drugs to treat the disease.

They found that a protein released by fat tissue in mice causes insulin resistance, a primary risk factor for diabetes. Elevated levels of the protein had also previously been detected in patients suffering from diabetes.

"Being resistant to insulin is one of the major causes of diabetes," said Dr Barbara Kahn of Beth Israel Deaconess medical Center in Boston, Massachusetts, and the lead author of the research published in the science journal Nature.

"And in the absence of diabetes, insulin resistance is a major risk factor for heart disease and early mortality."

Insulin, which is produced by the pancreas, regulates blood sugar levels. People with type 1 diabetes, which accounts for 10-25 percent of cases, do not produce any insulin that helps glucose, or sugar, from food get into cells.

Type 2 diabetes, the most common form of the disease, is caused by an inability to make enough, or to properly use, insulin. About 90 percent of diabetes sufferers have type 2, which is linked to being overweight or obese.

About 150 million people worldwide suffer from diabetes and the number may double by 2025, according to the World Health Organization.

The scientists found the protein, called retinol binding protein (RBP4), by studying mice which had been genetically engineered to over or under produce another protein linked to insulin resistance.

They also discovered that increasing levels of RBP4 caused insulin resistance while decreasing levels relieved the condition.

In people who are obese or suffer from type 2 diabetes excess amounts of RBP4 are linked to the severity of insulin resistance.

"There is a rapidly increasing epidemic of obesity and type 2 diabetes in the western world," said Khan.

"It is, therefore, clear that more effective treatment strategies are needed to prevent and treat diabetes. RBP4 could prove to be a novel target for developing anti-diabetic therapies," she added.