Parkinson’s Disease and Diabetes: Is There a Link?

Michael J. Fox, from the “Family Ties” TV series and “Back to the Future” movies, recently shared his experience and life with Parkinson’s disease on “CBS Mornings.” You’ve likely heard about this condition, but maybe you’re wondering exactly what it is, who it affects, and if it impacts people with diabetes. Learn more about this disease and how you might be able to reduce your risk.

What is Parkinson’s disease?

The American Parkinson Disease Association defines Parkinson’s disease (PD) as “a type of movement disorder that can affect the ability to perform common, daily activities. It is a chronic and progressive disease, meaning that the symptoms become worse over time.”

What causes Parkinson’s disease?

If nerve cells (neurons) in an area of the brain called the substantia nigra become damaged or die, less dopamine is produced. Dopamine is a brain chemical that allows brain cells to communicate. Lower dopamine levels cause abnormal brain activity, which can cause issues with movement.

PD also results in the loss of another brain chemical called norepinephrine, which is needed for the functioning of digestion, heart rate, blood pressure, and breathing.

“Genetics cause about 10% to 15%of all Parkinson’s,” says the Parkinson’s Foundation. But environmental and lifestyle factors play a role, too, including a head injury, area of residence, and exposure to certain toxic chemicals. But the exact cause of PD is unknown.

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What are the symptoms of Parkinson’s disease?

Symptoms of PD usually develop slowly over years, and the Parkinson’s Foundation says that the progression of symptoms can vary from person to person. Early signs of PD can be quite mild and even go unnoticed. Typical symptoms, however, include:

Tremor (shaking) in one hand, foot, or leg that eventually affects both sides of the body
Slowed movement (bradykinesia), which makes daily tasks more difficult
Rigid or stiff muscles that may be mistaken for arthritis or an orthopedic injury
Posture and balance problems that include an inability to stay upright or prevent a fall
Unsteady walking and coordination problems
Muscle twisting, spasm, or cramping
Changes in facial expressions
Speech changes
Handwriting changes
Problems chewing and swallowing

Other symptoms can occur, as well, such as cognitive decline, trouble sleeping, depression, and constipation.

There are five stages of PD, with stage one consisting of mild symptoms that usually don’t interfere with daily activities. Stage five is the most advance stage and may include an inability to walk; a person in this stage may need a wheelchair or be bedridden.

Most people with PD die with this condition, not from it, says the American Parkinson Disease Association. An increased risk of falls with resulting injury as well as aspiration pneumonia can lower the lifespan of someone with PD. However, PD is not fatal: by managing the condition and making healthy lifestyle choices, you can lead a full, happy life.

What are the risk factors for Parkinson’s disease?

Risk factors for PD include:

Older age — people aged 60 or older have a higher risk than younger people
Heredity — if PD runs in the family, your risk of getting it is increased
Gender — men are more likely to get PD than women
Environmental factors — exposure to pesticides, herbicides, heavy metals, and other toxic chemicals may increase the risk
Head trauma — blows to the head likely increases the risk of PD (of note, Muhammed Ali had PD)

How is Parkinson’s disease diagnosed?

There is no one test that diagnoses PD. A doctor will review your medical and family history, current symptoms, and do a neurological and physical exam. The Parkinson’s Foundation states that two of the four main symptoms must be present for PD to be diagnosed:

Shaking or tremor
Slowness of movement, called bradykinesia
Stiffness or rigidity of the arms, legs, or trunk
Trouble with balance and possible falls, also called postural instability

You will likely be referred to a neurologist if your primary care provider believes that you may have PD. Imaging tests may be recommended to rule out other possible causes of your symptoms.

How is Parkinson’s disease treated?

There’s no cure for PD, but medications are available to help control symptoms. These include carbidopa-levodopa, often in combination with other classes of medications such as dopamine agonists, MAO inhibitors, COMT inhibitors, and anticholinergic agents.

Physical, occupational, and speech therapy may be recommended, as well. Deep brain stimulation (DBS), which involves implanting an electrode into a specific part of the brain, may be indicated for those with advanced PD.

A healthy eating plan, regular physical activity, and therapies such as massage, tai chi, yoga, Alexander technique, and meditation are important, useful adjuncts to medications for managing PD.

How is diabetes linked with Parkinson’s disease?

Studies show that having type 2 diabetes increases the risk of PD, in part, due to insulin resistance and hyperglycemia (high blood glucose). One study, published in the journal Movement Disorders on March 8, 2021, looked at more than 33,000 articles, and from that analysis, revealed that people with type 2 diabetes were 1.21 times more likely to develop PD. Also, having type 2 diabetes causes a faster progression of motor symptoms and cognitive decline in PD.

On a brighter note, the authors of the study concluded that “Treating T2D may slow down the progression of Parkinson’s.” Some diabetes medications may actually lower the risk of PD. For example, the risk of PD was 36-60% lower in people with type 2 diabetes taking GLP-1 agonists or DPP4 inhibitors, according to a study published in an October 2020 issue of the journal Brain.