April 7 (HealthDay News) -- Use of the antipsychotic medication olanzapine may put a person at an increased risk for heart disease and type 2 diabetes, new findings show.

A team of French researchers studying the drug's effect on male rats found that, after consuming olanzapine over several weeks, the rodents' blood sugar levels rose significantly compared to rats not on the drug. This was especially noticeable after the rats ate meals with glucose in them. The rats consuming olanzapine did not gain weight or increase their food intake; however, the proportion of fat stored in their abdominal cavity was notably higher.

These changes are increased risk factors of metabolic syndrome, which puts an individual at greater risk of heart disease and type 2 diabetes.

"Based on these findings, we concluded that male rats treated with olanzapine experienced an early disruption of energy metabolism. This was a result of the fat tissue we observed and the impairment in blood sugar regulation which are both associated with metabolic syndrome and subsequent risk of diabetes," senior study author Dominique Hermier, of the Department of Human Nutrition, INRA, in Paris, said in a prepared statement.

The study was to be presented Monday at the Experimental Biology annual meeting, in San Diego.

Olanzapine is a part of the second generation of antipsychotics known as atypical antipsychotics being used to treat schizophrenia. These newer medicines have proven as effective as their predecessors in treating the delusions and hallucinations that accompany psychotic mental illness and even more effective in combating other symptoms, such as apathy. Side effects, though, include weight gain and a greater chance for developing metabolic syndrome. Physicians fear these side effects may cause their patients to stop taking their medicine.

"Atypical medications like olanzapine are of tremendous value in treating individuals with certain kinds of mental illness. Our hope is that through discoveries such as this one, such life-enhancing medicines can be further optimized," Hermier said.

SOURCE: American Physiological Society, news release, April 7, 2008