Oral Glucose Loading Modulates Plasma β-Amyloid Level in Alzheimer's Disease Patients: Potential Diagnostic Method for Alzheimer's Disease

Background: Although plasma beta-amyloid (A beta) has been suggested to be a noninvasive diagnostic biomarker for Alzheimer's disease (AD), its significance and validity have been inconclusive. Thus, it is quite important to establish a novel diagnostic method related to plasma A beta. Methods: As our previous animal studies demonstrated a relation of glucose with plasma A beta, we examined the effect of glucose loading on plasma A beta levels in AD patients. After fasting, an oral glucose load was administered to AD patients and non-AD dementia patients, and subsequently, blood glucose, plasma insulin, and plasma A beta levels were measured. Results: The plasma levels of baseline blood glucose, plasma insulin, and plasma A beta were not different between the two groups. However, immediately after glucose loading, a significant increase in plasma A beta 40 and A beta 42 levels was observed in AD patients, whereas a mild decrease in plasma A beta 40 and A beta 42 levels was detected in non-AD dementia patients. Conclusion: The present study clearly demonstrated a different response in plasma A beta 40 and A beta 42 levels after glucose loading between AD and non-AD dementia patients, which is consistent with our previous animal studies. These findings suggest a novel diagnostic tool for AD using the elevation of plasma A beta level after glucose loading, although further studies are necessary. Copyright (C) 2012 S. Karger AG, Basel