Having type 1 diabetes is associated with a higher risk of developing dementia, according to a study published March 18, 2026, in Neurology®, the medical journal of the American Academy of Neurology. Type 2 diabetes is also associated with a higher risk of dementia compared with not having diabetes. This study shows an association and does not prove that diabetes causes dementia.
Type 1 diabetes is rare, accounting for about 5% of diabetes cases.
“As advances in medical care have extended the lives of people with type 1 diabetes, it’s becoming increasingly important to understand the relation of type 1 diabetes to the risk of dementia,” said study author Jennifer Weuve, MPH, ScD, of Boston University. “We have known that type 2 diabetes is linked to an increased risk of dementia, but this new research suggests that, unfortunately, the association may be even stronger for those with type 1 diabetes.”
The study involved 283,772 people with an average age of 64. Of those, 5,442 had type 1 diabetes and 51,511 had type 2 diabetes. The participants were followed for an average of 2.4 years. During that time, 2,348 people developed dementia, including 144 of the people with type 1 diabetes, or 2.6%; 942 of the people with type 2 diabetes, or 1.8%; and 1,262 of the 226,819 people who did not have diabetes, or 0.6%.
After accounting for factors, such as age and education level, the researchers estimated that people with type 1 diabetes were nearly three times as likely to develop dementia as people without diabetes. People with type 2 diabetes were twice as likely to develop dementia as people without diabetes. Weuve added that in this study, an estimated 65% of dementia cases among people with type 1 diabetes could be attributed to the condition itself.
“Type 1 diabetes is not common, so this condition accounts for a small fraction of all dementia cases. But for the growing number of people with type 1 diabetes who are over 65 years old, these findings underscore the urgency of understanding the ways in which type 1 diabetes influences dementia risk and how we can prevent or delay it,” Weuve said.
A limitation of the study is that diabetes and dementia were identified using electronic health records and survey data, which may not capture every diagnosis.
The study was supported by the National Institutes of Health.
Source:
Journal reference:
Pederson, A. M., Buto, P., Zimmerman, S. C., Velez, M., Sims, K. D., Murchland, A. R., Wang, J., Brennan, A. T., Glymour, M. M., & Weuve, J. (2026). Type 1 Diabetes and Incident Dementia. Neurology. DOI: 10.1212/wnl.000000000021480. https://www.neurology.org/doi/10.1212/WNL.0000000000214805