Xiang Qi, PhD, an assistant professor at the NYU Rory Meyers College of Nursing in New York City, says the magnitude of this increased risk was striking.
“As medical advances allow more people with type 1 diabetes to age into their sixties and beyond, we’re only now beginning to see the full picture of how this condition affects long-term brain health,” he says.
Nearly 3 Times the Risk of Dementia in People With Type 1 Diabetes
The study analyzed more than 275,000 adults ages 50 and older from the All of Us health research program, a nationwide U.S. health database.
Among the participants, about 5,000 had type 1 diabetes and about 50,000 had type 2 diabetes.
Researchers followed the participants for an average of about two and a half years using electronic health records to identify new dementia diagnoses. About 2,000 participants developed dementia, which broke down into:
- 2.6 percent of people with type 1 diabetes
- 1.8 percent of people with type 2 diabetes
- 0.6 percent of people without diabetes
After accounting for factors like age and education level, the research team estimated that compared with people without diabetes:
- People with type 1 diabetes were almost 3 times as likely to develop dementia.
- People with type 2 diabetes were about twice as likely to develop dementia.
In addition, the connection between diabetes and dementia was similar across men, women, and racial and ethnic subgroups, suggesting that the link appears to be consistent in different populations.
“The most important takeaway is that individuals with type 1 diabetes appear to face a substantially higher rate of dementia than do those without diabetes,” says study coauthor Jennifer Weuve, ScD, a professor of epidemiology at Boston University.
The findings also suggest that type 1 and type 2 diabetes, though they share much in common, may contribute to dementia development in ways that are distinct from each other, she says.
“By clarifying whether and how dementia risks differ for people with type 1 diabetes, this research provides evidence to inform future research priorities, clinical awareness, care planning, and prevention strategies,” she says.
How Might Type 1 Diabetes Be Driving Dementia Risk?
There are several biological mechanisms may be at play when it comes to type 1 diabetes and dementia risk, including:
- High blood sugar levels, which can damage blood vessels and brain tissue
- Hypoglycemia, or low blood sugar levels, which can also damage brain cells
- Inflammation and oxidative stress, which may affect memory-related brain regions
“All forms of diabetes affect blood vessels, including those in the brain, and vascular damage increases dementia risk,” says Michal Schnaider Beeri, PhD, director of the Herbert and Jacqueline Krieger Klein Alzheimer’s Research Center at Rutgers University in New Brunswick, New Jersey.
The Study Sheds New Light on Type 1 Diabetes Specifically
The study doesn’t prove that diabetes directly causes dementia. But it does add to evidence that metabolic diseases can have long-term effects on brain health — and it fills an important evidence gap, Qi says. “Most prior research has either focused on type 2 diabetes or grouped all diabetes together. With more than 5,000 participants with type 1 diabetes, this is one of the largest studies to examine dementia risk in this population.”
“Clarifying that relation is more important than ever, now that individuals with type 1 diabetes are living to older ages,” she says.
The authors pointed out the findings are limited by the use of electronic health records and survey data to determine disease status, which could leave room for error.
“It’s also worth noting that individuals with type 1 diabetes tend to have more frequent healthcare encounters, which could lead to earlier detection of cognitive decline,” Qi adds.
What to Know if You Have Type 1 Diabetes
Because type 1 diabetes may come with age-related neurologic risks, managing the disease is important for protecting cognitive health. Qi recommends:
- Optimize blood sugar control to minimize both highs and lows.
- Stay physically and cognitively active.
- Manage heart disease risk factors.
- Have regular discussions with your healthcare team about cognitive health.
Schnaider Beeri also recommends that people with type 1 diabetes keep an eye out for early cognitive changes, which can affect the ability to stick to diabetes treatment safely and effectively.
“If cognitive decline goes unrecognized, it may create a negative cycle of poorer diabetes management,” she says, “leading to greater metabolic instability and vascular damage, which in turn may accelerate further cognitive decline.”