Q. I have type 2 diabetes, and among other things I’m worried that it may increase my chances of getting Alzheimer disease. Does diabetes affect the brain?

A. Many researchers think so. People with type 2 diabetes are resistant to insulin, and many are obese and have high blood pressure and cardiovascular disease. Each of these conditions has been identified as a risk factor for Alzheimer disease, in which there is a gradual loss of brain function. Indeed, one study found that people with diabetes face a 65% increased risk of developing Alzheimer disease.

Excessive blood levels of insulin—as occur in type 2 diabetes—may damage the brain by stimulating inflammation and thereby increasing levels of a toxic protein called beta-amyloid, a hallmark of Alzheimer disease.

In preliminary research, the insulin-sensitizing drug Avandia (rosiglitazone) improved memory in some people with mild to moderate Alzheimer disease. The drug may work in part by reducing inflammation or by boosting the capacity of brain cells to produce energy.

Most encouraging, lifestyle changes that improve diabetes show similar bene fits for Alzheimer symptoms. For example, moderate exercise reduces the risk of diabetes and improves mood and memory in older people. And carbohydrates that have a low glycemic index, such as whole grains and pasta, result in better memory performance than foods that speed sugar into the bloodstream. In addition, eating fish high in omega-3 fats has been shown to reduce the risk of memory loss and Alzheimer disease.