And because the study only looked at the relationship between blood glucose and dementia, it can't definitively say that higher blood sugar levels lead to memory loss, or that lowering blood sugar can reduce a person's risk.
"People who had lower blood sugar had lower risk than people who had higher blood sugar," Crane said. "That's not the same thing as saying that lowering your own blood sugar through any means has any influence on your personal risk of dementia," he added.
Other studies will need to test that theory more directly. Until more is known, Crane said exercise appears to be a good way to lower your personal risk of dementia.
"There's a lot of observational data to suggest that exercise is good for your brain, and exercise is one means to lower your blood sugar," he said. "I tell my patients to exercise."
For more information on risk factors for Alzheimer's disease, see the Alzheimer's Association.
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