Does untreated diabetes increase dementia rates? Yes, research shows a clear link where untreated or poorly managed diabetes raises the risk of dementia and related brain issues.
Diabetes happens when blood sugar levels stay too high because the body cannot use insulin properly. Insulin is a hormone that helps cells turn sugar into energy. When diabetes goes untreated, high blood sugar harms blood vessels and nerves over time. This damage affects the brain, speeding up problems like memory loss and confusion.
Studies find that people with diabetes have a much higher chance of dementia than those without it. For example, meta-analyses report a 73 percent higher risk of dementia and a 56 percent higher risk of Alzheimer’s disease in diabetes patients compared to non-diabetics. Type 2 diabetes alone boosts Alzheimer’s risk by more than 50 percent. Even pre-diabetes, where blood sugar is higher than normal but not yet diabetic, adds danger.
The risk grows worse with poor control. Untreated or inadequately treated diabetes leads to insulin resistance in the brain, especially in areas like the hippocampus that handle memory. This resistance makes brain cells struggle with energy, increases inflammation, and builds up toxic proteins like amyloid-beta and tau. These changes cause cognitive decline. Long-standing disease, obesity, vascular problems, and high HbA1c levels over 7 percent make it even riskier. Frailty combined with poor glycemic control speeds up brain aging.
Keeping blood sugar at normal levels helps protect the brain and improves thinking skills. Experts note that early diabetes management can lower overall cognitive decline. Older adults with diabetes face higher chances of cognitive issues and needing care facilities. Midlife diabetes onset is a key risk factor for late-life dementia.
Physical activity in middle and later years also cuts dementia risk sharply, by up to 45 percent for the most active people. This benefit starts strongest past midlife, even if not active earlier.
Sources
https://pmc.ncbi.nlm.nih.gov/articles/PMC12753325/
https://gulfnews.com/lifestyle/could-type-3-diabetes-harm-your-brain-what-your-blood-sugar-levels-mean-for-alzheimers-risk-1.500377397
https://baptisthealth.net/baptist-health-news/staying-active-as-you-age-past-midlife-sharply-lowers-dementia-risk
https://alz-journals.onlinelibrary.wiley.com/doi/10.1002/alz.71002?af=R
https://pubmed.ncbi.nlm.nih.gov/41452151/?fc=None&ff=20251228081836&v=2.18.0.post22+67771e2
https://diabetesjournals.org/care/article/49/Supplement_1/S277/163921/13-Older-Adults-Standards-of-Care-in-Diabetes-2026
https://nuffieldclinic.com/could-your-blood-sugar-be-affecting-how-you-think-remember-and-decide/
