Both types of diabetes dramatically increase a person’s risk of dementia, a new study says.

People with Type 1 diabetes are nearly three times more likely than those without diabetes to develop dementia, and folks with Type 2 diabetes are twice as likely to do so, researchers reported March 18 in the journal Neurology.

This is one of the first major studies to draw a link between dementia and Type 1 diabetes, an autoimmune disorder in which the body can’t produce enough insulin, researchers said.

“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 senior researcher Jennifer Weuve, a professor of epidemiology at 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,” Weuve said in a news release.

About 5% of all diabetes cases are Type 1, researchers noted, and the rest are Type 2.

Type 2 diabetes occurs in people who’ve developed resistance to insulin. Their bodies can still make insulin, but it isn’t as effective.

For the new study, researchers tracked nearly 284,000 people with an average age of 64. Of those, 5,442 had Type 1 diabetes and 51,511 had Type 2 diabetes.

During a follow-up of more than two years, about 3% of people with Type 1 diabetes and 2% of people with Type 2 developed dementia.

Overall, Type 1 diabetics were 2.8 times more likely to develop dementia, and Type 2 diabetics were 2 times as likely, the study found.

In all, about 65% of dementia cases among people in the study with Type 2 diabetes could be attributed to the condition itself, Weuve said.

Diabetes might increase dementia risk through brain cell damage from high blood sugar, increased deposits of toxic proteins linked to Alzheimer’s disease, or blood vessel damage that can lead to stroke, researchers speculated.

“Type 1 diabetes is not common, so this condition accounts for a small fraction of all dementia cases,” Weuve said. “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.”