Type 1 diabetes triples risk of dementia

Researchers report that people with type 1 diabetes are nearly three times as likely to develop dementia compared to those without type 1 diabetes.

The findings appeared in a study published on March 18, 2026, in Neurology, the medical journal of the American Academy of Neurology.

“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, professor in the Department of Epidemiology of the Boston University School of Public Health (BUSPH). “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.”

As background, the authors noted that type 2 diabetes is an established determinant of dementia risk, but that the influence of type 1 diabetes on dementia risk has remained unclear. “We evaluated associations of T1DM [type 1 diabetes] and T2DM [type 2 diabetes], separately, with incident dementia using linked electronic health records (EHRs).” they said.

The investigators extracted data on 283,772 subjects in a USA database. They were 50 years and older, with an average age of 64 (56.7% female) Enrollment began in 2017, with data available through October 2023.

At enrollment.  5,442 subjects had type 1 diabetes and 51,511 had type 2 diabetes.

The subjects were followed for an average of 2.4 years. During that time, 2,348 subjects developed dementia, including 144 of those with type 1 diabetes (2.6%), 942 of those with type 2 diabetes (1.8%) and 1,262 of the 226,819 subjects who did not have diabetes at baseline (0.6%).

After the investigators adjusted their findings for factors such as age and education, they estimated that the subjects with type 1 diabetes were about three times as likely to develop dementia compared to those without type 1 diabetes.

Notably, they also found that the subjects with type 2 diabetes were twice as likely to develop dementia as those without diabetes.

Dr. Weuve said that an estimated 65% of dementia cases among the subjects with type 1 diabetes could be attributed to the condition itself.

Results were similar across sex, race, and ethnicity strata.

“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.