What Is The Connection Between Insulin Resistance And Parkinson’s Disease?

You’ve probably heard of insulin resistance, but what is it, and why is it so important? 

Insulin is a hormone produced by the pancreas and helps to lower blood sugar levels.

It releases in small amounts continuously and in more significant quantities in response to blood sugar rises, such as after eating or in times of stress.

Insulin resistance occurs when the body doesn’t respond to insulin the way it should. When this happens, the pancreas releases even more insulin.

Over time, this can wear the pancreas out and reduce its ability to produce enough insulin, which can result in diabetes mellitus (diabetes).

However, insulin resistance also links with other health problems such as Parkinson’s disease.

The brain and diabetes 

Insulin is an important hormone most known for lowering blood sugar, such as after eating a meal. However, insulin plays another vast and vital role in regulating cognitive functions in the brain.

Cells in the brain can become insulin resistant. When this occurs, the likelihood of neurocognitive disorders such as Parkinson’s disease increases, as well as an increased risk of dementia.

Glucose (sugar) is the sole fuel for the brain to use as energy to perform its vital functions to keep the body alive.

Unlike other parts of the body, the brain can’t store energy. This lack of fuel storage means it requires a constant supply of glucose. If there is insulin resistance in the brain’s cells, then glucose can’t enter the cells where it’s needed.

Insulin resistance also tends to increase inflammatory responses in the body. The hypothalamus is the part of the brain responsible for regulating hunger, thirst, and other mechanisms that keep the body balanced. It contains a high density of insulin receptors and can become damaged due to inflammation.

When this occurs, there is a higher risk of developing diabetes mellitus. This inflammation can cause changes in the hormones that impact appetite and satiety (ghrelin and leptin). This can cause weight gain and obesity, which are risk factors for type 2 diabetes.

Alzheimer’s disease is a type of dementia that is so interconnected to diabetes that it’s often referred to as type 3 diabetes. While the exact physical processes aren’t completely clear, diabetes seems to change the brain to reduce blood flow, which is a leading cause of dementia.

People with diabetes also are at increased risk of vascular diseases, partially from the hardening of arteries, which can restrict blood flow to the brain and lead to cognitive decline.

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What is the link between insulin resistance and Parkinson’s disease?

Per the Mayo Clinic, “Parkinson’s disease (PD) is a progressive nervous system disorder that affects movement.

Symptoms start gradually, sometimes starting with a barely noticeable tremor in just one hand. Tremors are common, but the disorder also commonly causes stiffness or slowing of movement.”

More specifically, neurons of the substantia nigra in the brain have degenerated with PD. The substantia nigra is involved in the movement, which is why PD patients have difficulties with movement. 

Some of the symptoms of Parkinson’s include: 

  • Tremors

  • Slowed movement

  • Rigid muscles

  • Muscle stiffness

  • Loss of automatic movements such as blinking and smiling   

  • Speech changes    

  • Writing changes

Risk Factors for Parkinson’s Disease

As far as risk factors, PD incidence increases with age; most people get the disease starting around 60.

Men are more likely than women to develop Parkinson’s disease. There is also a genetic mutation that causes PDl. Another risk factor includes exposure to certain toxins or other environmental triggers.

Recent studies have found a connection between insulin resistance and Parkinson’s disease. Having insulin resistance and metabolic syndrome seems to worsen outcomes and increases the risk of Parkinson’s. 

Metabolic syndrome is a term for the combination of being overweight or obese with increased visceral fat (fat around the abdomen and vital organs), prediabetes or diabetes, high blood pressure, and high cholesterol or high triglycerides.

Another study found that nearly two-thirds of PD patients had insulin resistance. The interesting thing about that study is not all people with insulin resistance have high blood sugar, and not all were overweight. Therefore, lean PD patients can still have insulin resistance.

There are also studies suggesting that insulin resistance can interfere with dopamine functioning in the brain. Dopamine is a neurotransmitter that allows our brain to send messages to nerves throughout the body.

PD patients are believed to have a lack of dopamine production, which is another reason Parkinson’s disease patients tend to have insulin resistance.

In addition, the substantia nigra, which becomes degenerated, contains dopaminergic neurons, meaning they are essential in the production of dopamine.

Insulin resistance management 

Insulin resistance can precede type 2 diabetes by 10-15 years, meaning you can have undiagnosed insulin resistance for a long time. This means that there are several years where you can improve insulin resistance and help prevent type 2 diabetes mellitus.

Having insulin resistance and high blood sugar levels causes prediabetes. This is the term for having borderline high blood sugars but not high enough to be considered diabetes. While diabetes is a disease that isn’t reversible, prediabetes is reversible through lifestyle changes.

Many studies suggest that a high amount of free fatty acids in your blood can cause your body to not respond to insulin effectively. Eating more calories than you burn, gaining weight, and carrying extra weight can all increase the amount of free fatty acids in your blood.

Ways to manage insulin resistance and reduce insulin levels include

There are many ways you can manage insulin resistance and improve insulin sensitivity.

Watch your weight

Many people with insulin resistance are overweight, but some lean people can develop insulin resistance as well. If you’re overweight, losing 5-10% of your body weight can significantly lower your chance of developing diabetes. 

Be physically active

Exercise helps improve insulin resistance. Being physically active can also boost your metabolism, helping to shed extra pounds in those wanting to lose weight. Aim for at least 150 minutes per week of moderate to vigorous physical activity such as swimming, brisk walking, jogging, or other activities you enjoy that gets your heart pumping.

Reduce your sugar intake

Added sugars are prevalent in many processed foods, which many people rely on due to convenience. It’s estimated that up to 74% of processed foods contain added sugar.

Eat a balanced diet

A healthy diet low in refined sugars and carbohydrates and rich in plant-based foods can reduce insulin resistance and the prevalence of type 2 diabetes. The Mediterranean diet is a perfect example of this healthy eating and links with reduced insulin resistance.

The current Recommended Daily Allowance (RDA) for added sugar is 50 grams or less. In contrast, The American Heart Association recommends that women don’t consume more than 6 teaspoons (24 grams) of added sugar per day, and men keep their added sugar intake below 9 teaspoons (36 grams) per day.

However, the average American adult consumes around 77 grams of added sugar per day! Added sugars raise blood sugar more quickly than sugars found naturally in foods. When blood sugar levels rise quickly, the pancreas releases a larger amount of insulin, which can worsen insulin resistance.

First, to cut back on your added sugar intake, check the ingredients list on the nutrition facts label and look for added sugars. Many ingredients are added sugars, so it can sneak up in many forms!

The new Nutrition Facts label has a line for added sugars, making spotting added sugars even easier.


Having insulin resistance means that your body’s cells don’t respond to insulin effectively. Insulin resistance can result in higher blood sugar levels and eventually diabetes.

Insulin resistance is also linked with an increased risk of Parkinson’s disease (PD), a neurodegenerative disease that impacts speech, movement, and coordination.

Improving insulin resistance can reduce PD incidence, which you can do through healthy lifestyle changes such as getting regular physical activity, eating a healthy diet, and losing weight if you’re overweight.

Explore More

how to reverse insulin resistance

10 Natural Ways To Improve Insulin Resistance.


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  3. Mark A. Creager, Thomas F. Lüscher, and prepared with the assistance of, Francesco Cosentino, and Joshua A. Beckman. Diabetes and Vascular Disease. Pathophysiology, Clinical Consequences, and Medical Therapy: Part I. 2003. Available from: https://www.ahajournals.org/doi/full/10.1161/01.cir.0000091257.27563.32
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  6. Parkinson’s Foundation. Parkinson’s Disease and Insulin Resistance. Available from: https://www.parkinson.org/blog/science-news/science-article/Parkinsons-Disease-Insulin-Resistance-HOMA
  7. Cedars-Sinai. Exploring the Link Between Dopamine and Parkinson’s Disease. 2017. Available from: https://www.cedars-sinai.org/blog/exploring-the-link-between-dopamine-and-parkinsons-disease.html
  8. The American Heart Association. Added Sugars. 2018. Available from: https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/sugar/added-sugars
  9. The American Heart Association. How much sugar is too much? Available from: https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/sugar/how-much-sugar-is-too-much
  10. Institute for Responsible Nutrition. Learn to recognize the 56 different names for sugar. Available from: https://www.responsiblefoods.org/sugar_names/

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