Harvard Health Letter

Protect your memory and thinking skills

Keeping your blood sugar level in check may help ward off dementia.

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Here's another reason to keep your blood sugar under control: increased levels of any kind are now linked to an increased risk of developing dementia. "For the first time, we have a convincing link between dementia and elevated blood sugars, even in the nondiabetic range," says Dr. David Nathan, a Harvard Medical School professor and the director of the Diabetes Center and Clinical Research Center at Massachusetts General Hospital.

Blood sugar risks

Blood sugar levels rise every time you eat. If the levels are too high—126 milligrams per deciliter of blood (mg/dL) or more after an eight-hour fast—you have type 2 diabetes. We've known for a long time that there are links between diabetes and dementia. However, a recent study found that all blood sugar increases—even without diabetes—are associated with an increased dementia risk; the higher the blood sugar, the higher the risk. "We speculate that high blood sugar levels are causing more vascular disease," says
Dr. Nathan, who was an author on the study.

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