Illness and disease don’t exist in silos: often, one can trigger or exacerbate another. Emerging evidence is painting a clearer, more urgent picture: the global epidemic of diabetes may be one of the strongest, yet most controllable risk factors for developing dementia. Far from being two separate conditions, researchers are increasingly recognizing them as a single, intertwined metabolic crisis affecting both the body and the brain.
What is Diabetes?
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Before we can talk about how diabetes and dementia are linked, we have to understand each disease individually. Diabetes Mellitus is a group of diseases characterized by high levels of glucose (sugar) in the blood, resulting from the body’s inability to produce or properly use insulin. Insulin is a hormone produced by the pancreas that acts like a key, allowing glucose (the body’s main energy source) to enter the cells. There are two types of diabetes:
- Type 1 (T1D): An autoimmune condition where the body does not produce insulin.
- Type 2 (T2D): A condition, typically developed later in life, where the body either does not produce enough insulin or, more commonly, the cells become resistant to the insulin it does produce.
Uncontrolled blood sugar over time can damage blood vessels and nerves throughout the body, leading to complications like heart disease, kidney failure, and nerve damage (neuropathy).
What is Dementia?
Dementia is not a specific disease but an umbrella term for a group of symptoms caused by damage to brain cells. It involves a decline in memory, thinking, problem-solving, and language that is severe enough to interfere with daily life. While aging is the greatest risk factor, dementia is not a normal part of aging. The most common types of dementia include:
- Alzheimer’s disease: Caused by abnormal buildup of proteins (beta-amyloid plaques and tau tangles) in the brain, leading to cell death.
- Vascular dementia: Caused by impaired blood flow to the brain, often due to a stroke or damage to the small blood vessels. This results in brain cells dying from a lack of oxygen.
The Intertwined Crisis: How Diabetes and Dementia Connect
The connection between diabetes and dementia is so strong that some researchers have unofficially dubbed Alzheimer’s disease “Type 3 Diabetes”. This link is driven by several mechanisms.
Shared Vascular Damage
Both diabetes and dementia are significantly driven by cardiovascular problems. Diabetes damages blood vessels, including those in the brain, which is the direct cause of vascular dementia. This damage is aggravated by co-existing conditions like high blood pressure, high cholesterol, and obesity.
Brain Insulin Resistance
Like muscle and fat cells, brain cells rely on insulin to regulate energy use and promote cell health. In people with diabetes, brain cells may become insulin-resistant, hindering their ability to use glucose for energy. This energy deprivation is thought to promote the accumulation of the toxic amyloid and tau proteins associated with Alzheimer’s.
Chronic Inflammation
Diabetes involves a state of chronic, low-grade inflammation throughout the body. This affects the brain, as well. In the brain, this inflammation can damage neurons and disrupt the communication networks that are essential for healthy cognition.
The Latest Evidence: Study Findings Linking Diabetes and Dementia
Recent findings presented at the European Association for the study of Diabetes in Vienna, Austria, have reinforced the connection between the two conditions. They have also highlighted the groups that are most at-risk. This includes:
Increase Mortality Risk in T2D
A 20-year multinational study covering millions of individuals found that dementia-related mortality rose sharply after age 80. There was a clear excess risk among individuals with Type 2 Diabetes compared to those without the disease.
Increased Dementia Risk in T1D
Research from the Swedish National Diabetes Registry found that individuals with Type 1 Diabetes had a twofold increased risk for all-cause dementia. Furthermore, these individuals had an almost fourfold risk for vascular dementia. This risk was strongly correlated with poor glycemic control (high A1c levels) and longer disease duration. This suggests that the management of blood sugar is critical for brain health.
The Role of Immune Markers
The REVADIAB study investigated the link between glycemic variability, cognitive function, and circulating immune markers in T1D. It found a significant correlation between certain immune markers, suggesting underlying chronic inflammation, and lower cognitive performance. This further supports the theory that diabetes-related inflammation negatively impacts the brain.
Dementia’s Many Faces: Other Causes and Risk Factors
Just because you don’t have diabetes, doesn’t mean you have nothing to worry about when it comes to dementia prevention. While the diabetes-dementia link is powerful, numerous other factors can lead to cognitive decline. Dementia is multi-factorial, meaning it is often caused by a combination of issues:
Neurodegenerative Causes
The most common is Alzheimer’s disease itself, which involves plaque and tangle pathology. There are other neurodegenerative conditions that cause dementia as well. Lewy Body dementia is another, which involves the depositing of abnormal proteins called lewy bodies in the brain. Also, Frontotemporal dementia, which involves damage to the frontal and temporal lobes.
Lifestyle and Health Risks
Beyond diabetes, there are several, mostly preventable, factors that contribute to dementia risk. These include:
- Age and genetics (called non-modifiable factors)
- High blood pressure and high cholesterol
- Lack of physical activity and poor diet
- Smoking and excessive alcohol consumption
- Depression
- hearing loss
- Traumatic brain injury
Read More: Can Your Eyes Reveal Diabetes or Cancer? Don’t Miss the Signs
Beyond the Diagnosis: Why You May Be At Risk Even Without Diabetes
It is crucial to understand that a formal diagnosis of diabetes is not the only criteria for an elevated dementia risk. The real danger often lies in an underlying cluster of health conditions known as Metabolic Syndrome (MetS). MetS is defined as having excess belly fat plus at least two of the following:
- High blood pressure
- High blood sugar (even if not yet full diabetes)
- High triglycerides (a type of fat in the blood)
- Low “good” HDL cholesterol
Even if your blood sugar is not high enough for a diabetes diagnosis, these individual components are quietly wreaking havoc on your vascular system and brain. Studies show that MetS in mid-life is associated with a significantly higher risk of dementia, including Alzheimer’s and vascular dementia. This means the silent, unhealthy metabolic processes that lead to diabetes are already active and damaging the brain years before a person receives a diabetes label.
What This Means For Us
For those of us that have diabetes, no matter the type, this means that it is of critical importance that blood sugar is kept under control. The data is here and it is clear: uncontrolled diabetes will likely eventually lead to dementia. For all of us, including those with diabetes, addressing the individual components of metabolic syndrome is of the utmost importance. This includes managing blood pressure, losing weight if necessary, and controlling cholesterol.
The Bottom Line
Essentially, living a healthy lifestyle is the most powerful strategy for reducing dementia risk, regardless of diabetes status. Weight management, stress management, healthy diet, regular movement and exercise, and proper sleep hygiene will all work to mitigate your dementia risk. While you can’t control everything, a healthy lifestyle will make the uncontrollable risk factors much less relevant.
Disclaimer: This information is not intended to be a substitute for professional medical advice, diagnosis or treatment and is for information only. Always seek the advice of your physician or another qualified health provider with any questions about your medical condition and/or current medication. Do not disregard professional medical advice or delay seeking advice or treatment because of something you have read here.
Read More: The 5 Early Behavioral Changes That Signal Signs of Dementia