Cholesterol is a fat-like substance naturally produced by your liver. It circulates in the blood and contributes to many important functions, like making hormones and vitamin D.

Some conditions and behaviors can cause high cholesterol, or hypercholesterolemia. About 38% of U.S. adults have high cholesterol, according to the Centers for Disease Control and Prevention (CDC).

Over time, high cholesterol can lead to heart disease, the leading cause of death in the United States. Heart disease increases your risk of heart attack and stroke.

It’s possible to develop high cholesterol on its own. But often, it’s a comorbidity, meaning it can appear with other chronic conditions.

Having comorbidities increases your risk of complications. So, it’s important to manage these conditions and consider how they might interact.

Read on to learn about high cholesterol as a comorbidity, plus how it might affect other conditions.

What is high cholesterol?

High cholesterol means your total blood cholesterol levels are 200 mg/dL or higher. Doctors consider healthy cholesterol levels to be less than 200 mg/dL.

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Comorbidity is when you have more than one condition at the same time. These conditions are usually chronic, meaning that they need long-term treatment or management.

Comorbid conditions are also called:

  • coexisting conditions
  • co-occurring conditions
  • multimorbidity
  • multiple chronic conditions

A comorbidity is different from a complication. A complication is a medical problem that develops during a disease or treatment. Complications can also occur after a procedure.

Comorbidities are significant because they increase your risk of complications. For example, the conditions might cause or worsen each other.

Your doctor will also need to consider all your conditions when treating each one.

High cholesterol often coexists with the following conditions:

Obesity

Obesity is a disease involving excess body fat. It occurs when your body mass index (BMI) is over 30.

High cholesterol commonly appears with obesity. This is due to several reasons, according to a 2020 article.

First, the excess fat in obesity causes your liver to overproduce very-low-density-lipoprotein (VLDL) cholesterol, or “bad” cholesterol.

Excess body fat also causes inflammation. This triggers VLDL production and decreases HDL cholesterol, or “good” cholesterol.

Considering weight loss surgery?

To qualify for bariatric surgery, you must have a BMI of 40 or more. Alternatively, you can have a BMI of 35 or more and at least one obesity-related comorbidity. High cholesterol is a valid comorbidity for bariatric surgery.

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Diabetes

High cholesterol is a comorbidity of diabetes, a disease that causes high blood sugar due to insulin deficiency or resistance.

Insulin is a hormone that helps your cells take up glucose, or sugar, for energy. This helps regulate blood glucose levels. In insulin deficiency, your body doesn’t produce insulin, so your cells are unable to properly take up glucose.

According to a 2016 article, insulin deficiency and resistance change how your body produces cholesterol. This can cause high cholesterol levels. When this happens, it’s known as diabetic dyslipidemia.

Heart disease

High cholesterol is a major risk factor for heart disease. As a result, the two conditions often appear together.

According to a 2021 article, high cholesterol can lead to atherosclerosis, or the buildup of plaque in your blood vessels.

Atherosclerotic plaque, or fatty deposits, is made of:

  • cholesterol
  • cellular waste products
  • fatty substances
  • fibrin (a blood-clotting protein)

Over time, atherosclerotic plaque can reduce blood flow to your heart. This increases your risk of heart disease, heart attack, and stroke.

Hypertension

High cholesterol and hypertension, or high blood pressure, are the two major risk factors for heart disease. They’re also comorbid conditions.

High cholesterol and hypertension share many risk factors, as listed by the CDC:

  • unhealthy diet
  • lack of physical activity
  • obesity
  • age

Additionally, high cholesterol can contribute to hypertension. Excess cholesterol can build up in the blood vessels, causing atherosclerosis. This makes your blood vessels narrow and rigid, reducing blood flow and increasing blood pressure.

Arthritis

Arthritis is an inflammatory joint condition. It’s a comorbidity of several conditions, including high cholesterol.

This is partly related to inflammation. According to a 2017 scientific review, high LDL cholesterol can increase inflammation, potentially contributing to arthritis.

High cholesterol may also increase oxidative stress, causing cartilage damage. Cartilage is the tissue in your joints.

Additionally, high cholesterol and arthritis often coexist because they share risk factors. These include:

  • obesity
  • high blood pressure
  • smoking cigarettes

Obstructive sleep apnea

High cholesterol is a comorbidity for obstructive sleep apnea, a sleep disorder. Sleep apnea happens when your upper airways repeatedly collapse during sleep, which interrupts breathing.

A 2017 study found that people with sleep apnea are more likely to have high cholesterol. The condition may trigger inflammation and oxidative stress, potentially contributing to increased blood cholesterol levels.

Also, like high cholesterol, sleep apnea often appears with conditions like:

  • diabetes
  • obesity
  • atherosclerosis

Atrial fibrillation

Atrial fibrillation (AF or AFib) is a type of arrhythmia, or irregular heart rate. It happens when the upper and lower chambers of the heart beat out of sync.

High cholesterol is associated with a higher risk of AFib, according to a 2019 study. More research is needed to understand the link, but it may be related to high cholesterol altering the tissue in the heart.

Also, high cholesterol and AFib may coexist because they share risk factors:

  • older age
  • high blood pressure
  • heart disease
  • obesity
  • sleep apnea
  • diabetes

High cholesterol and COVID-19

According to a 2020 study, people with obesity who have high LDL cholesterol have a higher risk of getting COVID-19.

However, the CDC has not confirmed that high cholesterol and COVID-19 are comorbidities.

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If you have high cholesterol, your doctor will likely recommend the following:

  • Dietary changes: This includes eating more fruits, veggies, and unsaturated fats. It also includes limiting foods high in saturated fats, sodium, and sugar.
  • Exercise: Aim for 2 hours and 30 minutes of moderate physical activity per week.
  • Avoid or quit smoking: If you smoke cigarettes, your doctor can help you quit.
  • Take medication: You might need to take cholesterol-lowering medications called statins. It’s important to take these medications in addition to making lifestyle changes.

These lifestyle modifications can also manage other conditions that appear with high cholesterol.

Depending on these conditions, your doctor may suggest additional therapies or medications to help you stay healthy.

High cholesterol is a major risk factor for heart disease. It can develop on its own or with other conditions known as comorbidities. This can increase the risk of complications.

Comorbidities of high cholesterol include obesity, diabetes, hypertension, and heart disease. It can also coexist with arthritis, sleep apnea, and atrial fibrillation.

In many cases, managing high cholesterol will help manage other conditions. Your doctor can provide personalized guidance depending on your comorbidities.