Type 1 Diabetes Linked to Higher Risk of Dementia.
Type 1 Diabetes Linked to Higher Risk of Dementia
A new study found that people with type 1 and type 2 diabetes were more than twice as likely to develop dementia, but those with type 1 diabetes were at greatest risk.
Both type 1 and type 2 diabetes are associated with an increased risk of developing dementia, but people with type 1 diabetes are at greatest risk of the neurological disease, according to a new study led by researchers at the School of Public Health.
Published in the journal Neurology, the study found that people with type 1 diabetes were nearly three times more likely to develop dementia than people without diabetes, while those with type 2 diabetes were twice as likely. These findings held irrespective of gender, race, or ethnicity.
Diabetes affects all ages and is the seventh-leading cause of death in the United States.. Type 2 diabetes accounts for the vast majority of diabetes diagnoses, with type 1 diabetes comprising only about five percent of cases.
Few studies have distinguished the dementia risks between persons with type 1 and type 2 diabetes, and the new study is among the largest to explore this subject. Improvements in treatments for type 1 diabetes have extended the lives of people living with this disease; as this population continues to live longer, it is important to understand, and ultimately reduce, age-related health risks associated with type 1 diabetes.
“These findings extend prior research that has largely focused on type 2 diabetes by demonstrating that dementia risk is also substantially elevated among individuals with type 1 diabetes,” says study lead author Annie Pederson, research fellow in the Department of Epidemiology. “Understanding this long-term cognitive risk is important for prevention.”
For the study, Pederson and colleagues used data from surveys and electronic health records among nearly 284,000 participants in the ongoing All of Us research program, a convenience sample of US adults. They developed an algorithm to distinguish between type 1 and type 2 diabetes on the basis of the health records, and then validated that information against two reference measures: self-reported diabetes type and the amount C-peptide in the individual’s blood. From an average age of 64, the participants were followed for 2.4 years on average between 2017 and 2023. Among the study group, 5,442 people had type 1 diabetes and 51,511 people had type 2 diabetes. Over the follow-up, 2,348 people developed dementia, including 2.6 percent of people with type 1 diabetes and 1.8 percent of people with type 2 diabetes.
Compared with participants who did not have diabetes, the rate of dementia onset was 2.8 as great among those with type 1 diabetes and 2.1 times as great among those with type 2 diabetes. Nearly 65 percent of newly diagnosed dementia among patients with type 1 diabetes could be attributed to their diabetes status.
Both type 1 and type 2 diabetes may impair cognitive function through chronic metabolic dysfunction and blood vessel damage, but some mechanisms may be unique to diabetes type, Pederson says.
“Type 2 diabetes is primarily driven by insulin resistance and hyperglycemia, which can promote vascular injury and neurodegenerative processes,” she says. “Type 1 diabetes is characterized by autoimmune beta cell dysfunction and insulin dependence, which may increase dementia risk through recurrent hypoglycemia and related mechanisms.”
National estimates suggest that nearly 30 million Americans have been diagnosed with diabetes, and an additional 11 million people are unaware that they have the disease. As diagnosed cases are expected to rise substantially to 60 million by 2060, more research is needed to continue evaluating the association between dementia risk and diabetes types.
“To better understand elevated risk among those with type 1 diabetes, we are currently examining how the presence of other clinical conditions may contribute to dementia risk in individuals with type 1 diabetes,” says study senior and corresponding author Jennifer Weuve, professor of epidemiology. “Identifying these so-called ‘risk modifiers’ could help identify subgroups who face the highest risk of dementia and inform more targeted prevention and clinical care strategies.”
The study was coauthored by several researchers in SPH’s Department of Epidemiology, including Peter Buto, research fellow; Scott Zimmerman, senior research fellow; Kendra Sims, assistant professor; Audrey Merchland, postdoctoral associate; and Maria Glymour, chair and professor. The study was also coauthored by Mabeline Velez, an instructor in SPH’s Department of Health Law, Policy & Management; Alana Brennan, SPH associate professor of global health; and Jingxuan Wang, a visiting scholar at SPH.