The researchers determined that the main reason why diabetic people age 60 and older scored low on a cognitive function test was because of improper management of their disease.
"We knew that there was an association between diabetes and dementia in older people," said Yousef Mohammad, a study co-author and an assistant professor of neurology at Ohio State University. "But we found out that there is a difference in cognitive capability between diabetics whose disease is under control and those whose disease isn't adequately controlled."
According to the Centers for Disease Control and Prevention, more than 16 million people in the United States have diabetes and about 800,000 new cases are diagnosed each year.
"The prevalence of dementia will likely increase as the U.S. population ages," he said. "Diabetes is already on the rise."
The researchers presented their findings in April at the American Academy of Neurology conference in Honolulu.
They evaluated the association between diabetes mellitus status and cognitive function in 2,583 adults aged 60 and older who had participated in the third National Health and Nutrition Examination Survey, an ongoing study sponsored by the Centers for Disease Control and Prevention.
The participants were grouped according to their diabetic status: poorly controlled diabetes; adequately controlled diabetes; those with impaired glucose tolerance, when blood glucose levels are between normal and diabetic levels; and a non-diabetic control group.
The researchers ran blood glucose tolerance tests and hemoglobin A1C measurements on each participant. The hemoglobin A1C test tells a doctor whether or not the patient's glucose levels are under control, while a blood glucose tests indicates if a patient's glucose tolerance is impaired.
Cognitive ability was measured by a series of questions, including asking participants who and where he was; if he could remember objects he had seen a few minutes earlier; if he could complete simple addition and subtraction problems; and if he could recall a story he had heard five minutes earlier.
Eight percent (205) of the participants scored low on the cognitive abilities test. It turned out that only those participants with poorly controlled diabetes had low scores on the cognitive abilities test.
Mohammad said the next step is to find out if getting mismanaged diabetes under control can reverse dementia associated with the disease.
"Many diabetics take insulin or other hypoglycemic drugs, but the disease still isn't controlled," he said. "It could be that these patients aren't taking their medications properly, or that they're not taking a strong enough dose."
While the association between dementia and diabetes is clear, researchers don't fully understand the mechanism of how diabetes triggers dementia.
"If we can help diabetics control their disease, then we may be able to lower the incidence of dementia in this population," Mohammad said. "That's crucial, because treatment for dementia is very limited."
Mohammad conducted the study with Adnan Qureshi, Amir Siddiqui, Jawad Kirmani, Andrew Xavier, and Adnan Safdar, all with the University of Medicine and Dentistry of New Jersey in Newark, and M. Fareed Suri, of Case Western Reserve University.
# Contact: Yousef Mohammad, 614-293-4974; Mohammadfirstname.lastname@example.org Written by Holly Wagner, 614-292-8310; Wagner.email@example.com