What Is Insulin Resistance?
Insulin resistance is a condition in which the body’s cells no longer respond properly to insulin. Insulin is an important hormone produced by the pancreas that helps regulate our blood sugar levels. When cells become resistant to insulin, it can lead to abnormally high blood sugar or hyperglycemia, which can increase the risk of developing type 2 diabetes and other serious metabolic health conditions.
What Causes Insulin Resistance?
One of the primary causes of insulin resistance is the long-term consumption of a diet that is high in unhealthy processed foods, sugar, and saturated fats. Chronic, ongoing exposure to a diet that is high in sugar places huge demands on the continual release of insulin to moderate blood sugar levels.
The fundamental job of insulin is to move sugar from the outside of our cells in our circulation (i.e. our blood sugar) to inside our cells, where it can be used and burned for energy. The constant, repetitive ‘wearing down’ of this process results in the cells becoming ineffective at transporting sugar, making them resistant to insulin, and this is how we end up with high blood sugar levels (hyperglycemia).
In addition to a diet that is chronically high in foods that place pressure on blood sugar, insulin resistance is also far more likely to occur if you are carrying additional weight beyond what is suited to your BMI and not being active and exercising enough.
How Does Insulin Resistance Affect The Brain?
A well-functioning brain places high demands on our internal energy resources to perform its many functions. As a result, even subtle changes to blood sugar control will have a ripple effect on overall brain health.
Research shows that insulin control is connected to cognitive performance. The inability to control blood sugar can set your body on a path for neurodegeneration. Prolonged high-sugar states can lead to inflammation and mitochondrial dysfunction (the cellular machinery we need to produce energy), both of which have consequences for brain health. Insulin resistance, if left unmanaged, can develop into Type 2 Diabetes, and diabetics are up to twice as likely to go on to develop Alzheimer’s disease as non-diabetics.
One of the signs of longer-term, uncontrolled blood sugar is called diabetic neuropathy. This is a type of damage to our nerves that occurs as a direct result of high circulating levels of blood sugar and triglycerides (fats). Moreover, it’s not just nerves that become damaged, but also small blood vessels, which are critical to delivering nutrients and oxygen to the nerves and brain. This lack of blood, nutrients and oxygen to nourish the brain and nerves will quickly show up as foggy thinking, slowed mental recall, and poor concentration and memory. Over the long term, if damage to nerves continues without dietary and lifestyle intervention, it can result in problems with coordination and the pathways of messages from the brain to organs.
How Can I Find Out If I Am At Risk For Insulin Resistance?
Working closely with your health professional for your preventative health goals will help ensure you can jump on long-term health risk factors, like insulin resistance. Your health professional can run screening tests to check your blood sugar and other associated health markers to understand your risk of developing insulin resistance or pre-diabetes. The most common test used is called HOMA-IR and is a combined measure of risk using blood glucose and fasting insulin. Continuous glucose monitors are also becoming more accessible and are a worthwhile way of getting data in real time about how specific food choices influence your blood sugar control.
Risk factors for insulin resistance include;
- Being 45 or older
- Family history of diabetes
- Metabolic conditions, such as PCOS, high cholesterol or blood pressure
- A known tendency for hyper or hypo (low) glycemia
- Being inactive
- Having a high BMI
- Sleep problems, such as sleep apnoea or insomnia
Signs you might have insulin resistance can include;
- Fatigue and becoming tired after meals
- Skin tags and pigmentation changes (darkening) to certain areas (Eg. underarms)
- Elevated thirst or more frequent urination
- Feeling hungry, even right after eating
Turning Insulin Resistance Around
If you discover you have insulin resistance, the good news is that many dietary and lifestyle changes can have a profound impact on turning insulin resistance around.
Getting smart with food choices, focusing on proper meal planning, and taking into account nutrient density, calories, and fibre can help give your body the nutritional resources it needs to manage blood sugar more efficiently. Decreasing your intake of sugar and carbohydrates can alleviate the load on your pancreas to pump out insulin and help to rebalance these stressed systems.
Making sure you’re active because not only does it help us lose weight by mopping up and burning calories, but movement provides improved oxygen and nutrient supply around the body and boosts our production of BDNF – an important nerve growth factor that has protective and restorative effects in the brain and nervous system. Aim for at least 30mins of dedicated movement daily.
Lastly, make sleep a priority. It’s the single most important and freely available therapy that anyone can access. Getting a minimum of 7 hours of quality sleep has protective health benefits. Sleep is anti-inflammatory and helps protect our brain and nervous system health. Sleep loss is a risk factor for poor insulin control and cognitive decline. It’s more important than you probably realise.
Managing blood sugar is a 100% modifiable risk factor that we can take personal control over with the choices we make daily.
It is well worth the effort when you consider just how many chronic illnesses that poor blood sugar control can lead to in the long term. With Alzheimer’s and dementia being one of the leading causes of death in both men and women, there is so much potential to decrease those statistics through diet and lifestyle modifications and exercise control over blood sugar in a more balanced and sustainable way.
Femminella GD, et al. Does insulin resistance influence neurodegeneration in non-diabetic Alzheimer’s subjects?. Alz Res Therapy 2021 Feb 17;13(47).
Cetinkalp S, et al. Insulin resistance in brain and possible therapeutic approaches. Curr Vasc Pharmacol. 2014;12(4):553-64. PMID: 23627981.
Willmann C, et al. Insulin sensitivity predicts cognitive decline in individuals with prediabetes. BMJ Open Diabetes Research and Care 2020;8:e001741.
American Diabetes Association. Insulin resistance and prediabetes. 2019.
National Institute of Diabetes and Digestive and Kidney Diseases. What is insulin resistance? 2019.
American Heart Association. Insulin resistance and prediabetes. 2021.