# The Connection Between Diabetes and Dementia Risk
People with diabetes face a significantly higher risk of developing dementia compared to those without the condition. Research shows that individuals with diabetes have a 56 percent higher risk of Alzheimer’s disease and a 73 percent higher risk of dementia overall when compared to non-diabetics.
The relationship between these two conditions is particularly strong in certain groups. People who have had diabetes for a long time, those with poor blood sugar control, individuals with obesity, those with vascular problems, or people with insulin resistance are especially vulnerable. The more uncontrolled someone’s diabetes is, the higher their dementia risk becomes.
One striking finding involves the connection between age and risk. Younger people who develop diabetes face an even greater risk of later being diagnosed with Alzheimer’s disease and dementia. Additionally, studies show that up to 81 percent of people with Alzheimer’s disease have either type 2 diabetes or prediabetes, suggesting that those with Alzheimer’s are more susceptible to developing diabetes as well.
The biological mechanisms behind this connection involve insulin resistance in the brain. Even people with Alzheimer’s disease who don’t have diabetes show signs of brain insulin resistance, particularly in the hippocampus, which is crucial for memory. When brain cells cannot use insulin effectively, they struggle to use glucose for energy. This energy shortage leads to weaker connections between nerve cells, making it harder to form new memories and contributing to cognitive decline.
The buildup of harmful proteins also plays a role. High blood sugar can cause beta amyloid clumps to form, which get stuck between nerve cells in the brain. Insulin resistance also triggers oxidative stress and inflammation within brain tissue. These processes, along with mitochondrial dysfunction, are key factors in the early development of Alzheimer’s disease.
Research has identified a specific protein called BACE1 that appears to be involved in this process. In people with type 2 diabetes, BACE1 levels increase under conditions of insulin resistance. Studies show that elevated plasma BACE1 levels in people with type 2 diabetes correlate with reduced cognitive scores. Additionally, high plasma BACE1 levels combined with insulin resistance in type 2 diabetes patients show a significant trend toward increased risk for mild cognitive impairment.
While diabetes hasn’t been proven to directly cause Alzheimer’s disease, the correlation is strong enough that experts recommend taking action early. Effective diabetes management has clear potential in reducing overall cognitive decline. Large studies demonstrate that poor blood sugar control significantly increases dementia risk.
However, there is currently a gap in clinical practice. There are no formal guidelines recommending routine Alzheimer’s screening in people with diabetes, despite the strong connection between the two conditions.
It’s worth noting that some research suggests other factors may also play important roles in cognitive decline. Age, education level, and genetic factors like the APOE4 allele are also strongly associated with cognitive impairment and dementia. These factors may interact with diabetes in complex ways that researchers are still working to understand.
The term “type 3 diabetes” has been coined by some researchers to describe the link between Alzheimer’s disease and insulin resistance in the brain. While the medical community, including the American Diabetes Association, has not yet officially recognized this as a distinct condition, growing research into the connection between blood sugar, insulin, and brain health may lead to changes in how these conditions are understood and treated in the future.
Sources
https://www.frontiersin.org/journals/dementia/articles/10.3389/frdem.2025.1730524/full
https://pmc.ncbi.nlm.nih.gov/articles/PMC12726522/
https://agsjournals.onlinelibrary.wiley.com/doi/10.1111/jgs.70231
