Metabolic Health and Your Brain | Windback NZ

Metabolic Health and Your Brain: Why Blood Sugar Today Shapes Cognitive Ageing Tomorrow

Disclaimer: The information in this article is for educational and general wellness purposes only. It is not a substitute for professional medical advice and is not intended to diagnose, treat, or cure any health condition. Always seek the guidance of a qualified healthcare professional before making changes to your diet, lifestyle, exercise routine, or supplement use, particularly if you have any existing medical conditions or concerns.

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Photo: We often think of foods like orange juice as “healthy”, yet because the fibre has been removed, it can behave more like liquid sugar – leading to faster, higher blood sugar spikes than many people realise.

From Blood Sugar Numbers to Brain Futures

Metabolic health is often discussed in terms of weight, diabetes and heart disease. Increasingly, researchers are highlighting another crucial link – the relationship between midlife metabolic health and how our brain ages.

Large population studies suggest that insulin resistance, elevated blood sugar and central adiposity in midlife are associated with higher risk of cognitive decline and dementia later in life. In other words, how we manage energy today may influence how clearly we think and how independent we remain decades from now.

Why the Brain Cares About Metabolism

The brain is a highly energy-demanding organ. Although it represents only a small percentage of body weight, it can use a significant proportion of the body’s resting energy. Glucose and ketones are key fuels, and insulin signalling influences how effectively brain cells use these fuels.

Insulin resistance in the body is associated with changes in how the brain handles glucose. Some researchers have used the term “type 3 diabetes” to reflect the role of impaired insulin signalling in the brain, although this is not an official medical diagnosis.
Vascular health matters because the brain relies on a dense network of blood vessels. High blood pressure, impaired endothelial function and unfavourable lipids can affect blood flow over time.
Inflammation and oxidative stress can affect synapses, mitochondria and neural networks involved in memory, mood and executive function.

This is why many functional medicine practitioners consider metabolic health a central pillar of brain health, not just a cardiometabolic issue.

“Type 3 Diabetes”: Definition and Controversy

“Type 3 diabetes” is a phrase you may see in books, podcasts or online discussions. It is used by some researchers to describe a potential link between Alzheimer’s disease and insulin resistance in the brain.

It is important to be clear that:

Type 3 diabetes is not an officially recognised medical diagnosis. It is a descriptive term used in some scientific papers and discussions, rather than a formal condition like Type 1 or Type 2 diabetes.
The idea behind the term is that insulin dysfunction in the brain may contribute to the changes seen in Alzheimer’s disease, in a similar way that insulin resistance affects the body in Type 2 diabetes.
The concept remains controversial and is still being explored. Not all clinicians or researchers agree on its usefulness.

What is more widely accepted is that people with Type 2 diabetes have a higher risk of developing Alzheimer’s disease and other forms of dementia over time. Insulin resistance, high blood sugar and vascular changes may all contribute to what is sometimes called “brain insulin resistance”.

Connection to Alzheimer’s Risk

Alzheimer’s disease is complex and influenced by many factors including age, genetics, vascular health, lifestyle and environment. Metabolic health is one piece of this puzzle.

Research suggests that:

Individuals with Type 2 diabetes have a higher risk of developing Alzheimer’s disease and other dementias compared with those without diabetes.
Insulin resistance in the brain may affect how brain cells use glucose, potentially contributing to cognitive decline.
Chronically high blood sugar and glucose variability may accelerate brain ageing, increase oxidative stress and affect small blood vessels that supply the brain.

This does not mean that everyone with diabetes will develop Alzheimer’s, or that blood sugar is the only factor that matters. It does highlight that supporting metabolic health is likely to be relevant for long term brain health, alongside many other lifestyle and medical considerations.

Symptoms and Diagnosis: Why Language Matters

At this stage, there is no formal diagnosis of “Type 3 diabetes”. Healthcare professionals diagnose conditions such as Type 2 diabetes, mild cognitive impairment, different forms of dementia and Alzheimer’s disease using established criteria.

Symptoms that are sometimes discussed in the context of “Type 3 diabetes” overlap with early Alzheimer’s disease and other cognitive conditions. These may include:

Progressive memory loss or forgetfulness that affects daily life
Difficulty completing familiar tasks
Changes in mood, personality or behaviour
Poor judgment or increasing difficulty with planning and decision making

If you or someone close to you notices these changes, it is important to seek medical assessment promptly. Early evaluation can help rule out reversible causes, support a clear diagnosis where possible and guide a personalised plan.

Lifestyle Foundations for Metabolic and Brain Health

Even though “Type 3 diabetes” is not a recognised diagnosis, the potential connection between metabolic health and brain ageing points us toward practical steps that can support both.

1. Build Blood Sugar Friendly Plates

Stabilising blood sugar is less about perfection and more about the average pattern of your meals.

Anchor meals with protein: Include a meaningful source at each meal, such as eggs, Greek yoghurt, fish, poultry, tofu or legumes.
Add fibre and colour: Non-starchy vegetables, lower sugar fruits and whole grains help slow the release of glucose and feed the gut microbiome.
Choose healthy fats: Olive oil, avocado, nuts, seeds and oily fish support satiety and cell membrane integrity.
Reduce ultra processed foods: Foods high in refined starches, sugars and industrial seed oils are associated with higher glucose variability and inflammatory load.

2. Train Muscle as a Metabolic Organ

Muscle is a major site of glucose disposal. Resistance training and regular movement increase muscle mass and insulin sensitivity, which helps keep blood sugar more stable over time.

Include strength or resistance training two to four times per week, adjusted to your level and any injuries.
Layer in low intensity movement, like walking or light cycling, especially after meals to support post-meal blood sugar.

3. Protect Sleep and Circadian Rhythm

Even a few nights of short or fragmented sleep can reduce insulin sensitivity and increase hunger hormones.

Get morning light within the first hour of waking where possible, which helps anchor your body clock and supports metabolic rhythm.
Wind down with dimmer, warmer light and reduced screens in the last hour before bed to support melatonin release and deeper sleep.

4. Manage Stress With Nervous System Tools

Chronic stress hormones can raise blood sugar and influence visceral fat over time. Practices such as slow breathing, time in nature, social connection and reframing can all help lower baseline stress load.

What Metabolic Experts Are Saying

Dr Casey Means, a physician focused on metabolic health, describes poor metabolic health as a “unifying root cause” behind many chronic conditions. She highlights that only a minority of adults meet criteria for optimal metabolic health, yet the tools for improvement are largely behavioural – food, movement, sleep, light and stress management.

Dr Mark Hyman has long championed the idea that food is information. He emphasises that what we eat can either promote stable blood sugar and low grade inflammation or drive the opposite. His work often focuses on whole foods, glycaemic load and the quality of fats as levers for long term brain and metabolic health.

Dr Andrew Huberman brings in the neuroscience of circadian rhythms, light and sleep. He notes that when sleep is compromised, insulin sensitivity is reduced, cravings change and decision making becomes harder, which can create a loop that undermines metabolic and brain health together.

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Looking After Your Future Brain

Metabolic health is not just about avoiding future diagnoses. It is about protecting how you think, feel and function as the years pass. By seeing food as information, movement as a metabolic signal and sleep as a nightly reset, you can begin to align your daily choices with the kind of brain and body you want in ten, twenty or thirty years.

General information: Information in this article is for educational purposes only and is not intended to diagnose, treat, cure or prevent any disease. Always read the label and use only as directed. Supplements should not replace a balanced diet or healthy lifestyle. If you are pregnant, breastfeeding, taking medication or have a medical condition, consult your healthcare practitioner before use. If symptoms persist, seek professional advice.