People with untreated type 2 diabetes developed Alzheimer’s disease 1.6x faster and had more tau protein in cerebrospinal fluid (CSF) compared to people without diabetes.

Tau tangles accumulate inside neurons and can disrupt many functions. Older adults with untreated type 2 diabetes had higher CSF tau than those without diabetes or those with treated type 2 diabetes. This study also found that people with untreated diabetes had a more rapid progression to dementia than people without diabetes.

While this study was an observational study which makes it difficult to establish causation, it suggests that high blood sugar that is not treated is linked to tau pathology which may accelerate dementia and Alzheimer’s disease.