Can untreated diabetes cause memory loss? Yes, leaving diabetes untreated can lead to high blood sugar levels that harm the brain and contribute to memory problems over time. High blood sugar, even before full diabetes develops, has been linked to worse performance on memory tests, like recalling words after a delay. In one study of healthy people without diabetes, those with slightly higher blood sugar remembered two fewer words after 30 minutes compared to those with lower levels. This happens because excess sugar in the blood may cause changes in brain areas key for learning and memory, such as the hippocampus.
Diabetes raises the risk of cognitive decline, which starts with subtle issues like slower thinking or minor memory slips and can progress to mild cognitive impairment or dementia. People with type 2 diabetes face higher chances of all-cause dementia, Alzheimer’s disease, and vascular dementia than those without it. Untreated or poorly managed diabetes worsens this through ongoing high blood sugar, insulin resistance, and inflammation, which damage brain cells and connections. Brain scans of diabetes patients often show loss of gray and white matter in memory-related regions like the frontal and temporal lobes.
Sometimes called “type 3 diabetes,” Alzheimer’s shares features with diabetes because the brain becomes resistant to insulin, starving nerve cells of energy even if blood sugar looks normal. This leads to weaker neuron links, inflammation, and buildup of harmful proteins like amyloid-beta and tau, all tied to memory loss. Both high and low blood sugar episodes from untreated diabetes hurt brain function, and longer diabetes duration makes problems worse. Older adults with diabetes are especially at risk for memory loss, executive function issues, and needing more care.
Keeping blood sugar in check through treatment helps protect memory. Studies show better glucose control links to stronger memory scores, and some diabetes drugs may lower dementia risk. Regular checkups, managing related issues like high blood pressure, and healthy habits can slow brain changes from untreated diabetes.
Sources
https://www.consultant360.com/story/higher-blood-sugar-tied-memory-problems-study
https://gulfnews.com/lifestyle/could-type-3-diabetes-harm-your-brain-what-your-blood-sugar-levels-mean-for-alzheimers-risk-1.500377397
https://pmc.ncbi.nlm.nih.gov/articles/PMC12753325/
https://pmc.ncbi.nlm.nih.gov/articles/PMC12690186/
https://www.zenhospital.in/the-hidden-complications-of-diabetes-beyond-blood-sugar-levels/
https://alz-journals.onlinelibrary.wiley.com/doi/10.1002/alz.71002?af=R
https://diabetesjournals.org/care/article/49/Supplement_1/S277/163921/13-Older-Adults-Standards-of-Care-in-Diabetes-2026
