People with diabetes have a higher risk of developing Alzheimer's disease — and doctors don't know why. But researchers have found that compared with Alzheimer's patients who never developed diabetes, those who had both conditions and received diabetes therapy had 80% fewer brain-clogging amyloid plaques, a physical sign of Alzheimer's. It's not clear why the treatment had this effect, but the hope is that diabetes drugs could reduce symptoms in some and provide clues to new treatments.