Prediabetes Linked to Cognitive Decline

Diabetes and the Brain

Scientists have known for years that having type 2 raises your risk for dementia. In fact, scientists have considered using the term type 3 diabetes to describe Alzheimer’s disease – a debilitating form of dementia that progressively impairs cognitive health. Why? Dementia is very much influenced by the mechanics of blood glucose levels and insulin resistance.

Studies suggest that insulin resistance and too high blood sugar levels may surpass other known causes of cognitive decline and Alzheimer’s disease. 

Insulin resistance is a hallmark symptom of type 2 diabetes. It leads to cells responding poorly to insulin and slowly becoming resistant to it. This causes sugar to remain in the bloodstream and rise to abnormally high levels, which can affect certain proteins in the brain. This is why type 2 diabetes is a risk factor for Alzheimer’s disease.

Prediabetes: Blood Sugar & Memory Loss

But it turns out, diabetes isn't the only problem. Prediabetes – a condition in which blood sugar levels are higher than normal, but not high enough to be considered diabetes – also raises the risk of cognitive decline and vascular dementia, according to a study published in Diabetes, Obesity and Metabolism. 

“Prediabetes is a common problem,” says Bernard Kaminetsky, MD, medical director, MDVIP. “About 88 million Americans have it; unfortunately, close to 85 percent don’t realize it.”

Researchers from University College of London obtained data on 500,000 people (including average blood sugar levels), ages 40 to 60, with an average age of 58 from the UK Biobank to evaluate the cognitive decline risk an individual with prediabetes had. Biobank data was then divided into categories by blood sugar levels – known diabetes, undiagnosed diabetes, prediabetes, normal blood sugar and low blood sugar. 

Between five and seven million participants had prediabetes. Researchers selected and recruited a sample size of almost 500,000 subjects with prediabetes from the database. Close to 500,000 subjects were tested for cognitive function and more than 18,000 had repeat follow up tests. And about 35,000 participants had an MRI scan performed. 

Researchers compared the performance of cognitive tests against the different blood sugar levels, brain structure and dementia diagnoses. They factored in age, sleep deprivation, education level, gender, smoking status, body mass index, cardiovascular disease and time lapse between cognitive tests. To identify relationships between these variables, researchers relied on a regression-based analysis. Here’s what they found prediabetes was associated with:

• Higher risk for vascular dementia, but not Alzheimer’s disease
• Smaller hippocampus (region of the brain that handles many memory functions)
• Brain lesions (often linked with age-related cognitive impairment)
• Results also suggested that diabetes raised the risk for vascular dementia three times higher than people with normal blood sugar levels and raised the risk for Alzheimer’s disease. 

Since the study is observational and doesn’t show cause and effect, researchers believe it should be replicated using different data sets.

How to Stop Prediabetes

“People often wait for a diabetes diagnosis before taking stock of their health. Their goal is usually controlling blood sugar and preventing complications,” says Kaminetsky. “However, lifestyle work should begin much earlier, and the goal should be preventing prediabetes.”

Preventing prediabetes begins with a healthy lifestyle -- eating a balanced, nutritious diet, exercising, maintaining a healthy weight and working closely with your doctor.

If you don’t have a doctor, consider partnering with MDVIP. MDVIP-affiliated physicians have the time and tools to develop a personalized wellness program for you that can help you lower your risk for diabetes and it’s complications. Find a physician near you and begin your partnership in health »