Blood Sugar and Your Brain: The Silent Ageing Factor

Adapted from a newsletter article by Annette Bosworth, M.D.

The Brain's Energy Demands

Your brain is an energy-intensive organ. Despite accounting for only about 2% of your body weight, it consumes approximately 20% of your body's energy resources. This disproportionate energy requirement highlights just how metabolically active your brain is, constantly working to maintain your level of consciousness, process information, regulate bodily functions, and store memories.

The Silent Threat: How Blood Sugar Ages Your Brain

Even when you feel perfectly fine, elevated blood sugar levels can be silently ageing your brain. This crucial insight has been confirmed by compelling evidence over recent years: average blood sugar and insulin levels are key predictors of brain health.

The Science: Trash Buildup in Your Brain

Your brain naturally produces proteins like tau and amyloid, often referred to as "trash" or "waste" when they accumulate. In a healthy brain, these proteins are efficiently cleared away by the cells. However, when average blood sugar rises above optimal levels, this crucial cleanup process becomes compromised, leading to buildup and potential damage.

Over time, this accumulation can result in:

• Cognitive decline

• Memory issues

• Neurodegenerative diseases

• Brain fog

• Decreased mental energy

When Blood Sugar Drops Too Low

On the flip side, low blood sugar (hypoglycemia) can cause immediate symptoms like:

• Difficulty concentrating

• Mental fog and confusion

• Irritability and mood changes

• Slowed reaction times

• In severe cases, loss of consciousness

Haemoglobin A1c: A Window into Brain Health

Hemoglobin A1c (HbA1c) reflects your average blood sugar over a three-month period, making it a valuable marker for assessing brain health risk. While conventional medicine often considers an A1c of 5.7% to be "normal," research suggests more optimal targets for brain protection:

• A1c of 5.0% equates to an average blood sugar of 5.4 mmol/L

• A1c of 5.7% translates to 6.4 mmol/L

While 6.4 mmol/L may seem safe by standard measures, it represents a threshold. Beyond this level, the risk of silent damage increases significantly, including mini-strokes that may occur without noticeable symptoms. These hidden cerebrovascular events can gradually erode memory, focus, and cognitive energy over time.

Keep Blood Sugar Below 5.6 mmol/L

For optimal brain health and protection against premature brain ageing, aim to maintain average blood sugar below 5.6 mmol/L — corresponding to an A1c of 5.0% or less. While this goal may be challenging to achieve, the reward is a sharper, more resilient brain as you age.

Insulin's Critical Role in Brain Health

While we often associate insulin with regulating blood sugar in the body, it also plays vital roles in the brain:

1. Insulin receptors are abundant in brain regions responsible for memory and learning

2. Insulin helps regulate neurotransmitters that affect mood and cognition

3. Proper insulin signaling supports neuroplasticity—the brain's ability to form new connections

When insulin resistance develops, these brain functions can deteriorate, potentially contributing to cognitive decline.

Strategies for Protecting Your Brain

To support optimal brain performance through healthy blood sugar management:

1. Target Ketones for Brain Fuel: Aim for morning ketones above 0.8 mmol/L, indicating efficient fat-burning and providing alternative brain fuel in the form of ketone bodies

2. Monitor Uric Acid Levels: As a marker of metabolic waste, keeping uric acid low helps minimize "trash" buildup in the brain

3. Limit Refined Carbohydrates and Sugars: These cause rapid blood sugar spikes and inflammation

4. Include Healthy Fats and Protein: These slow glucose absorption and provide steady energy

5. Consider Intermittent Fasting: This approach can improve insulin sensitivity

6. Stay Physically Active: Exercise enhances glucose metabolism and brain health

7. Prioritise Quality Sleep: Sleep is essential for metabolic regulation, neural repair and cell functioning

8. Manage Stress Levels: Stress hormones can raise blood sugar and damage brain tissue

The Ketone Alternative

When glucose availability is limited (by following a low-carbohydrate or ketogenic diet), your brain can adapt to using ketones—energy molecules produced during fat metabolism—for up to 70% of its energy needs. This metabolic flexibility offers a protective mechanism against energy disruptions and may provide more stable fuel for brain cells.

Many researchers are now investigating ketogenic approaches for various neurological conditions, as ketones provide a more consistent energy source that doesn't depend on fluctuating blood sugar levels.

Why Act Now?

The damage from elevated blood sugar is silent—by the time symptoms become noticeable, years of opportunity for prevention have already passed. The absence of symptoms does not mean absence of harm.

Protecting your brain requires proactive management of blood sugar levels, even when you feel perfectly fine. Maintaining blood sugar below 5.6 mmol/L is a powerful investment in your brain's future and cognitive longevity.

HbA1c and Average Blood Sugar Conversion

Conclusion

The relationship between blood sugar regulation and brain function underscores the importance of metabolic health for cognitive performance and longevity. By understanding this connection and taking action to maintain optimal blood sugar levels, you can help protect your brain from premature ageing and support cognitive function well into your later years.

This article was adapted from educational content by Dr. Boz. For more detailed information on this topic, please visit Dr. Boz's official website or consult with healthcare professionals for personalised advice.