Reported by Julielynn Wong, M.D., ABC News Medical Unit

High blood sugar levels may take a toll on the brain, a new study found.

The Australian study of nearly 250 non-diabetic men and women found those with high blood sugar levels tended to have shrinking in brain areas linked to memory and emotional processing. The results held up even after controlling for lifestyle factors such as smoking and weight.

"If replicated, this finding may contribute to a reevaluation of the concept of normal blood glucose levels and the definition of diabetes," wrote study author Dr. Nicolas Cherbuin, director of the Neuroimaging and Brain Lab at Australian National University in Canberra, Australia.

Previous research has linked diabetes, a disorder in which blood sugar levels are abnormally high, to age-related cognitive decline. But the new study, published Monday in the journal Neurology, suggested controlling blood sugar levels could boost cognitive health in non-diabetics.

How exactly? The jury's still out.

Some studies suggest blood sugar control can help regulate the body's inflammatory response, which has been linked to brain shrinkage. Another theory is that high sugar levels make the blood stickier, raising the risk of clots that starve the brain.

Either way, experts said, the study supports healthy eating to keep blood sugar levels in check.

"This in line with many other studies that have been published and adds to all of the data on diabetes affecting brain health," said Dr. R. Scott Turner, director of the Memory Disorders Program and a professor of neurology at Georgetown University Medical Center, who was not involved with this study.

For non-diabetic patients with high blood sugar levels, Turner recommended adopting the American Diabetes Association diet, which is high in non-starchy vegetables and low in carbohydrates and protein.