Diabetes appears to double a person’s risk of developing Alzheimer’s disease or other dementias, according to research in the September 20 issue of Neurology, the medical journal of the American Academy of Neurology.
“Diabetes is a common disorder, and the number of people with it has been growing in recent years all over the world,” said study author Yutaka Kiyohara, MD, PhD, of Kyushu University in Fukuoka, Japan. “Controlling diabetes is now more important than ever.”
According to the study, people with diabetes were more likely to develop Alzheimer's disease and other types of dementia, such as vascular dementia, which occurs when there is damage to blood vessels that deliver oxygen to the brain.
Researchers studied more than 1,000 people who were age 60 and older and given a glucose (sugar) tolerance test after an overnight fast to determine if they had diabetes. Study participants were monitored for an average of 11 years and then tested for cognitive impairments. During the study, 232 people eventually developed dementia.
The study found that people with diabetes were twice as likely to develop dementia as people with normal blood sugar levels. Of the 150 people with diabetes, 41 had developed dementia, compared to 115 of the 559 people without diabetes who developed dementia.
The results remained the same after the researchers accounted for factors such as high blood pressure, high cholesterol and smoking. The risk of dementia was also higher in people who did not have diabetes, but had impaired glucose tolerance, or were “pre-diabetes.”
In addition, the study found the risk of developing dementia significantly increased when blood sugar was still high two hours after a meal.