Diabetes Doesn't Seem to Affect Alzheimer's Disease Progression

Study looked at seniors' blood sugar tests along with their brain scans

  • Print

MONDAY, July 29 (HealthDay News) -- Conditions that cause problems maintaining normal blood sugar levels -- such as glucose intolerance, insulin resistance and type 2 diabetes -- don't appear to be linked to specific signs of Alzheimer's disease, new research indicates.

"When older folks develop dementia, it's usually from a host of factors [including Alzheimer's disease and hardening of the arteries]. Our study has shown that when older people with diabetes have dementia, it's not through Alzheimer's disease pathology," said senior study author Dr. Richard O'Brien.

However, O'Brien was quick to note that these findings don't mean that people with diabetes don't need to be concerned about their blood sugar levels. They do. "People with diabetes need to be good about blood sugar control," he said. "Atherosclerosis is a very important contributor to dementia in the elderly, and diabetes increases the risk of atherosclerosis."

O'Brien is a professor of neurology at the Johns Hopkins University School of Medicine, and chair of neurology at the Johns Hopkins Bayview Medical Center, in Baltimore. Results of the study were published online July 29 in JAMA Neurology.

O'Brien and his colleagues initiated the study because other research has suggested that problems with maintaining blood sugar levels, such as glucose intolerance and diabetes, increase the risk of Alzheimer's disease. O'Brien said some experts have even gone so far as to refer to Alzheimer's disease as "type 3 diabetes." (There's no such condition.)

Alzheimer's disease is the most common, but not the only, type of dementia. It occurs when deposits of amyloid beta (also known as plaques) build up in the brain along with twisted fibers of another protein (tangles), according to the Alzheimer's Foundation. Many people develop some plaques and tangles with age, but those with Alzheimer's disease have many more than the average person. Experts aren't sure exactly how this build-up of plaques and tangles may cause the symptoms of Alzheimer's disease.

There are several types of diabetes, but the most predominant is type 2 diabetes. Before developing type 2 diabetes, people generally show signs of insulin resistance and glucose intolerance. Insulin is a hormone that's necessary for the body to metabolize the carbohydrates in food and use the sugar (glucose) from those carbohydrates as fuel for the cells in body and brain.

If someone has insulin resistance, his or her body isn't using insulin efficiently, which allows glucose to build up in the blood. This is evident when someone does an oral glucose tolerance test. This test requires you to drink a sugar liquid, and then have your blood sugar levels tests at periodic intervals, such as at the start of the test, after an hour and then again after two hours. If you're insulin-resistant, the results of your oral glucose tolerance test will show higher levels of glucose than expected.

Such a finding indicates a higher risk of type 2 diabetes, according to the American Diabetes Association. Or, if the results are high enough, that may even indicate existing type 2 diabetes.

In the current study, the researchers followed 197 people who'd had at least two oral glucose tolerance tests during their lifetime. Thirty of these people had diabetes and were taking medications to control their diabetes. When these study volunteers died, autopsies of their brains were done. The average age at autopsy was 88.

A smaller group, consisting of 53 people who'd had two or more oral glucose tolerance tests, was also involved in the study. This group underwent positron emission tomography (PET) scans of their brains while they were alive. The average age at which they underwent imaging was 79.

The researchers found no significant correlation between glucose intolerance, insulin resistance or diabetes and the amount of amyloid beta in the brain, according to the study. That means that blood glucose levels likely don't contribute to the development of Alzheimer's disease specifically. Though, as O'Brien pointed out, blood glucose levels may still play a role in other types of dementia.

One expert said that the study scope may not be wide enough to allow definitive conclusions.

"There has been a lot of debate about diabetes and dementia. Is there a cause-and-effect relationship, or is it just an association? This study suggests that Alzheimer's isn't really related to insulin resistance and impaired glucose tolerance, but the number of patients with true diabetes was very small," said Dr. Joel Zonszein, director of the clinical diabetes center at Montefiore Medical Center, in New York City.

Zonszein said the study also doesn't look at the length of time someone has had diabetes, and whether or not it's well-controlled.

"We see a lot of people who have [small strokes] who have hypertension and type 2 diabetes," he said, noting that this can cause a lot of the symptoms of dementia, such as loss of memory. "Clinically, it's very difficult to tell the difference between dementia and Alzheimer's disease. And, although it may not be true [for] Alzheimer's disease, this won't mean any difference in current clinical practice."

"Early and aggressive treatment to control the blood sugar is the best treatment right now," he added. "Hopefully, with more studies, we can find out what medications are better for people with diabetes to help prevent dementia."

More information

Learn more about Alzheimer's disease from the Alzheimer's Foundation.

Fact Check

Fact Check

Have you found an error, or know of something we’ve missed in one of our stories?
Please use the form below and let us know.

* Required
  • Please post the headline of the story or the title of the video with the error.

  • Please post exactly what was wrong with the story.

  • Please indicate your source for the correct information.

  • Yes


  • This will only be used to contact you if we have a question about your submission, it will not be used to identify you or be published.

  • Cancel

Having problems with the form?

Contact Us Directly
  • Print

You can comment on most stories on You can also agree or disagree with other comments. All you need to do is be a Winnipeg Free Press print or e-edition subscriber to join the conversation and give your feedback.

You can comment on most stories on You can also agree or disagree with other comments. All you need to do is be a Winnipeg Free Press print or e-edition subscriber to join the conversation and give your feedback.

Have Your Say

New to commenting? Check out our Frequently Asked Questions.

Have Your Say

Comments are open to Winnipeg Free Press print or e-edition subscribers only. why?

Have Your Say

Comments are open to Winnipeg Free Press Subscribers only. why?

The Winnipeg Free Press does not necessarily endorse any of the views posted. By submitting your comment, you agree to our Terms and Conditions. These terms were revised effective April 16, 2010.


Make text: Larger | Smaller


Winnipeg Cheapskate: Cheap summer weekends

View more like this

Photo Store Gallery

  • A young gosling flaps his wings after taking a bath in the duck pond at St Vital Park Tuesday morning- - Day 21– June 12, 2012   (JOE BRYKSA / WINNIPEG FREE PRESS)
  • JOE.BRYKSA@FREEPRESS.MB.CA Local-(Standup photo)- Humming Around- A female ruby -throated hummingbird fly's through the bee bomb  flowers Friday at the Assiniboine Park English Garden- Nectar from flowers are their main source of food. Hummingbirds wings can beat as fast as 75x times second. Better get a glimpse of them soon the birds fly far south for the winter - from Mexico to South America- JOE BRYKSA/WINNIPEG FREE PRESS- Sept 10, 2009

View More Gallery Photos


Which of Manitoba's new landlord-tenant rules are you looking forward to most?

View Results

View Related Story

Ads by Google