THE QUESTION Might diabetes, which is increasing rapidly among U.S. residents, play a role in the development of dementia such as Alzheimer’s disease, also on the rise?

THIS STUDY involved 1,017 people, age 60 and older, who did not have dementia at the start of the study. Glucose tolerance tests given then showed that 458 of them had diabetes or pre-diabetes. Over the next 11 years, 232 people developed some type of dementia, including Alzheimer’s disease. Those with diabetes were about twice as likely to have developed dementia as were those with normal blood sugar levels. Pre-diabetes also increased the likelihood of a dementia diagnosis.

WHO MAY BE AFFECTED? Older people with diabetes, which affects more than 8 percent of the U.S. population, including nearly 19 million diagnosed with the disease and 7 million others who have diabetes but are not aware of it. Dementia is not a normal part of aging, but the risk for developing it increases with age. Today, more than 5 million Americans are living with Alzheimer’s, the most common type of dementia; that number is expected to triple by 2050.

CAVEATS Blood sugar levels were tested only at the start of the study. The study did not identify a biological connection between diabetes and dementia.

FIND THIS STUDY Sept. 20 issue of Neurology (www.neurology.

LEARN MORE ABOUT diabetes at Learn about dementia at

— Linda Searing

The research described in Quick Study comes from credible, peer-reviewed journals. Nonetheless, conclusive evidence about a treatment's effectiveness is rarely found in a single study. Anyone considering changing or beginning treatment of any kind should consult with a physician.