The link between blood sugar and dementia

Research increasingly shows that how you manage your blood sugar today can influence your brain health tomorrow. High or unstable blood sugar levels have been linked to a higher risk of cognitive decline and dementia, so managing blood sugar isn’t just about diabetes—it’s also about protecting your mind.

Understanding the blood sugar-brain connection

Your brain relies on glucose as its main source of energy. When blood sugar levels remain stable, the brain receives a constant supply of fuel to support memory, learning and decision-making.

However, frequent spikes and dips in blood sugar, often seen in diabetes or prediabetes, can disrupt this delicate balance and damage brain cells over time.

Here’s how poor blood sugar control can impact brain health:

• Insulin resistance: When the body responds less to insulin, glucose (sugar) has a harder time entering brain cells. This can lead to reduced brain energy and impaired communication between neurons.
• Inflammation: Chronic high blood sugar can trigger inflammation, which damages brain tissue and blood vessels that supply oxygen and nutrients.
• Oxidative stress: High glucose levels increase oxidative stress (an imbalance between destructive free radicals and antioxidants), which accelerates brain aging.
• Vascular damage: High blood sugar damages the small blood vessels in the brain, similar to its effects on the heart and kidneys, reducing blood flow and oxygen delivery.

How Blood Sugar Affects Dementia Risk

People with type 2 diabetes are at significantly higher risk of developing dementia and Alzheimer’s disease. Researchers have even coined the term “type 3 diabetes” to describe the brain’s resistance to insulin, a hallmark of Alzheimer’s disease.

The relationship is complex, but well established:

• Insulin plays a role in brain signalingand when it becomes less effective, memory and cognitive processing can suffer.
• Excess glucose and insulin in the blood can lead to a buildup of amyloid plaque, one of the pathological signs of Alzheimer’s disease.
• Diabetes-related complicationssuch as hypertension (high blood pressure) and heart disease, also increase the risk of dementia and further increase the risk of cognitive decline.

A 2024 study found that people with type 2 diabetes had a 50% to 75% higher risk of dementia than those without diabetes. This highlights the importance of regular screenings, early prevention and stable blood sugar management.

How to Reduce Sugar Consumption for Brain Health

You don’t have to be diabetic for sugar to impact your brain. Diets high in added sugars are associated with poorer memory, slower learning, cognitive decline, and increased risk of depression.

To maintain balanced blood sugar levels and protect your brain:

• Limit sugary drinks and desserts. Replace soda, sweetened tea, flavored coffee drinks, and fruit juices with water or unsweetened alternatives.
• Choose whole carbs. Opt for whole grains, beans, whole fruits and vegetables, which provide fiber to slow glucose absorption.
• Pair carbs with protein and/or healthy fats. This combination helps stabilize blood sugar levels and prolongs energy and feelings of fullness.
• Read labels carefully. Added sugars are often disguised under names like sucrose, corn syrup, rice syrup, molasses or agave nectar.

How to Support Brain Health Through Nutrition and Lifestyle

Although no food alone can prevent dementia, an overall balanced lifestyle can significantly reduce the risk. Focusing on whole foods, getting regular physical activity, and managing your blood sugar levels benefits both your body and your brain.

Consider these practical habits:

• Adopt a Mediterranean-style diet, DASH or MINDrich in fruits, nuts, fish and olive oil. These diets emphasize nutrient-rich, anti-inflammatory foods that support heart and brain health.
• Exercise regularlywhich improves insulin sensitivity and stimulates blood flow to the brain.
• Prioritize sleep and stress management, because both influence blood sugar regulation and cognitive health.
• Schedule regular checkups to monitor blood sugar, blood pressure and cholesterol.