Summary: As medical care allows people with Type 1 diabetes to live longer, a large new study of more than 280,000 adults finds a substantially higher association between Type 1 diabetes and dementia than previously recognized. The analysis suggests the dementia risk linked to Type 1 may exceed that seen with Type 2 diabetes, highlighting an emerging public health concern for aging people with Type 1 diabetes.
The study identifies an association, not proof of causation, but it points to an important “aging gap” as the population of older adults with Type 1 diabetes grows.
Key findings and statistics
- Relative risk: Compared with people without diabetes, those with Type 1 diabetes were about three times as likely to develop dementia; people with Type 2 diabetes were about two times as likely.
- Attributable fraction: The authors estimate that roughly 65% of dementia cases observed in the Type 1 group could be attributed to the condition, after accounting for measured confounders.
- Study population: 283,772 participants with a mean age of 64 were followed for an average of 2.4 years.
- Observed incidence:
- Type 1 diabetes: 2.6% developed dementia (144 of 5,442 people).
- Type 2 diabetes: 1.8% developed dementia (942 of 51,511 people).
- No diabetes: 0.6% developed dementia (1,262 of 226,819 people).
- Public-health context: Type 1 diabetes accounts for roughly 5% of all diabetes cases, but as people with Type 1 live longer, understanding its long-term effects on brain health has become a research priority for the National Institutes of Health.
Source: AAN
Summary of the published report: A study published March 18, 2026, in Neurology reports that having Type 1 diabetes was associated with a higher risk of being diagnosed with dementia. The study also found an elevated dementia risk among people with Type 2 diabetes compared with those without diabetes. The investigators emphasize that the work shows an association rather than direct proof that diabetes causes dementia.
Type 1 diabetes is relatively uncommon, representing approximately 5% of diabetes diagnoses. As survival improves, clinicians and researchers are increasingly focused on the long-term consequences of living with the disease into older age.
“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 investigation followed 283,772 people with a mean age of 64. Among them, 5,442 had Type 1 diabetes and 51,511 had Type 2 diabetes. Over an average follow-up of 2.4 years, 2,348 participants received a dementia diagnosis: 144 with Type 1 diabetes (2.6%), 942 with Type 2 diabetes (1.8%), and 1,262 among those without diabetes (0.6%).
After adjusting 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, while people with Type 2 diabetes were about twice as likely. The authors also report that, in this cohort, an estimated 65% of dementia cases among people with Type 1 diabetes could be attributed to the condition.
“Type 1 diabetes is not common, so this condition accounts for a small fraction of all dementia cases,” Weuve noted. “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 might prevent or delay it.”
The investigators acknowledge limitations: both diabetes status and dementia diagnoses were identified using electronic health records and survey data, which can miss cases or misclassify diagnoses. The authors stress that additional research with detailed clinical assessments and longer follow-up will help clarify mechanisms and timing.
Funding: The study was supported by the National Institutes of Health.
Questions answered in the report
A: The study does not establish a definitive cause, but one plausible explanation is that people with Type 1 diabetes experience a longer lifetime exposure to blood glucose variability. Decades of insulin management, including episodes of severe low blood sugar (hypoglycemia) and high blood sugar (hyperglycemia), could create a cumulative burden on cerebral blood vessels and neural tissue.
A: No. The findings describe an association across a large group, not a certainty for any individual. The purpose of this research is to encourage strategies to prevent or delay cognitive decline through better glucose management, targeted screening, and research into protective interventions for older adults with Type 1 diabetes.
A: The study used broad diagnostic information from health records that can include Alzheimer’s disease, vascular dementia, and other types. Diabetes has been especially linked with vascular cognitive impairment because prolonged high blood sugar can damage the brain’s small blood vessels, reducing oxygen and nutrient delivery and contributing to structural brain changes over time.
Editorial notes
- This article was edited by a Neuroscience News editor.
- The journal paper was reviewed in full by our editors.
- Additional context was added by our staff to clarify implications and limitations.
About this diabetes and dementia research news
Author: Renee Tessman
Source: AAN
Contact: Renee Tessman – AAN
Image credit: Neuroscience News
Original research: Findings reported in Neurology