Diabetics who take insulin plus a sulfonylurea diabetes pill have a lower risk of developing Alzheimer’s disease than diabetics who take insulin alone, researchers said.
They said the finding may help some diabetics lower their risk of developing the brain-wasting disease.
"Having an oral agent on board makes insulin more effective and lowers the risk for Alzheimer’s," said Dr. Sam Gandy, a researcher at Mount Sinai Medical Center in New York, who worked on the study.
The findings are significant as the number of people with Alzheimer’s, the most common form of dementia, is projected to rise steadily in coming decades as the proportion of elderly people in the U.S. population increases.
According to the U.S. Centers for Disease Control and Prevention, Alzheimer’s disease has just supplanted diabetes as the sixth-leading cause of death in the United States, with diabetes trailing close behind.
Several studies have found diabetics have a higher risk of getting Alzheimer’s than the general population. But researchers have found some diabetics have fewer Alzheimer’s-related changes in their brains than people who do not have diabetes.
Gandy and colleagues at Mount Sinai suspected the drugs diabetics were taking might be playing a role. They studied the brains of 124 people with diabetes who had died and 124 non-diabetics of comparable age, sex and severity of dementia.
People were classified according to the anti-diabetic drugs they had taken during their lifetime, including insulin only, diabetes medications other than insulin only or the use of both. Most had been taking one of the oldest types of diabetes pills, known as sulfonylureas.
The researchers measured the density of Alzheimer’s-related changes in the brain such as bundles of fibrous tangles of brain cells and sticky amyloid plaques.
People with diabetes who were treated with both insulin and a diabetes pill had 80 percent fewer amyloid plaques than people in all the other categories. The drugs did not seem to alter other Alzheimer’s-related brain characteristics.
"These results suggest that the combination of insulin and oral anti-diabetes medications may beneficially influence Alzheimer’s-related brain changes," Mount Sinai’s Michal Beeri, who led the study, said in a statement.
Presented at the International Conference on Alzheimer’s Disease in Chicago, Aug 2008