Extra Years With Kind 2 Diabetes, Increased Dementia Threat


By Amy Norton
HealthDay reporter

THURSDAY, April 29, 2021 (HealthDay News) – The younger people are when they develop type 2 diabetes, the higher the risk of dementia later in life, according to a new study.

Many studies have suggested links between diabetes and a higher risk of dementia. Experts say it’s likely because diabetes can damage the brain in a number of ways.

The new evidence suggests that younger people with diabetes may be at particular risk in the future.

By the age of 70, the study found that people recently diagnosed with type 2 diabetes were no higher risk of dementia than people without diabetes. The picture was different for people diagnosed over 10 years ago: they had twice the risk of dementia compared to people without diabetes at their age.

It may simply be because they have been living with diabetes for years.

“A younger age at the onset of diabetes means a longer duration, which allows any adverse effects of diabetes to develop over time,” said lead researcher Archana Singh-Manoux. She is a research professor at the University of Paris and at the French health institute INSERM.


Type 2 diabetes occurs when the body loses sensitivity to insulin, a hormone that regulates blood sugar. This results in chronically high blood sugar, which over time can damage both large and small blood vessels throughout the body.

These effects, which can affect blood flow to the brain, are one reason diabetes has been linked to dementia, Singh-Manoux said.

She also pointed out other possible pathways: insulin plays a role in brain function, and diabetes can prevent it from doing its job. Meanwhile, diabetes treatment can cause frequent episodes of low blood sugar that can damage the brain over long periods of time, Singh-Manoux said.

The results, published April 27 in the Journal of the American Medical Association, have far-reaching public health implications.

In the United States alone, more than 34 million people have diabetes, according to the American Diabetes Association, with the vast majority having type 2.

At one time, type 2 diabetes was a disease of older adults. However, with the ever increasing prevalence of obesity – a major risk factor for type 2 diabetes – the disease is increasingly being diagnosed in young people.


“The prevalence of diabetes continues to rise,” said Singh-Manoux, “and the age at the beginning is getting younger.”

That means more people are living longer with diabetes and are more prone to the complications of the disease. It is already known that the younger people are, the greater the risk of heart disease, stroke and premature death when diabetes occurs, Singh-Manoux said.

This study adds dementia to that list, she said.

The study included over 10,000 adults in the United Kingdom who were between 35 and 55 years old in the early 1980s. Over the next three decades, 1,710 people developed type 2 diabetes while 639 were diagnosed with dementia.

At the age of 70, people who had diabetes in the past five years were not at any higher risk of dementia than people without diabetes.

But those diagnosed more than 10 years ago showed their risk of dementia doubling. Their actual brain disease rate was 18 cases per 1,000 people per year, up from about nine cases per 1,000 in diabetes-free adults.


Overall, by age 70, the risk of dementia increased by 24% every five years that people with diabetes lived.

This is not a surprising finding, says Dr. Medha Munshi, director of the geriatric diabetes program at the Joslin Diabetes Center in Boston.

On the other hand, Munshi said, there is “some reassurance” in the lack of additional risk in older people who have recently been diagnosed with diabetes.

The question is whether younger diabetes patients can reduce their risk of dementia by better controlling their blood sugar.

Other studies, said Singh-Manoux, have found that people with well-controlled diabetes have slower mental decline than people with poor control. In this study, the risk of dementia is particularly high in diabetes patients who also developed heart disease.

According to Munshi, the key is that prevention starts early.

“People in their forties and fifties are usually not worried about dementia,” she said. “But this is the time to try to prevent it.”

Diabetes control often means taking medication or insulin, along with diet changes and regular exercise – both of which can have numerous long-term health benefits, according to Munshi.


“What we do in younger and middle ages will change how we end up in old age,” she said.

More information

The American Diabetes Association is more concerned with treating type 2 diabetes.

SOURCES: Archana Singh-Manoux, PhD, Research Professor, University of Paris, INSERM, Paris; Medha Munshi, MD, director of the Geriatric Diabetes Program, Joslin Diabetes Center, and associate professor of medicine at Harvard Medical School in Boston; American Medical Association Journal, April 27, 2021