Metabolic Syndrome

What Is

Metabolic syndrome is the name for a group of risk factors that raises your risk for heart disease and other health problems, such as diabetes and stroke.

The term "metabolic" refers to the biochemical processes involved in the body's normal functioning. Risk factors are traits, conditions, or habits that increase your chance of developing a disease.

In this article, "heart disease" refers to coronary heart disease (CHD). CHD is a condition in which a waxy substance called plaque builds up inside the coronary (heart) arteries.

Plaque hardens and narrows the arteries, reducing blood flow to your heart muscle. This can lead to chest pain, a heart attack, heart damage, or even death.

Metabolic Risk Factors

The five conditions described below are metabolic risk factors. You can have any one of these risk factors by itself, but they tend to occur together. You must have at least three metabolic risk factors to be diagnosed with metabolic syndrome.

  • A large waistline. This also is called abdominal obesity or "having an apple shape." Excess fat in the stomach area is a greater risk factor for heart disease than excess fat in other parts of the body, such as on the hips.
  • A high triglyceride level (or you're on medicine to treat high triglycerides). Triglycerides are a type of fat found in the blood.
  • A low HDL cholesterol level (or you're on medicine to treat low HDL cholesterol). HDL sometimes is called "good" cholesterol. This is because it helps remove cholesterol from your arteries. A low HDL cholesterol level raises your risk for heart disease.
  • High blood pressure (or you're on medicine to treat high blood pressure). Blood pressure is the force of blood pushing against the walls of your arteries as your heart pumps blood. If this pressure rises and stays high over time, it can damage your heart and lead to plaque buildup.
  • High fasting blood sugar (or you're on medicine to treat high blood sugar). Mildly high blood sugar may be an early sign of diabetes.

Overview

Your risk for heart disease, diabetes, and stroke increases with the number of metabolic risk factors you have. The risk of having metabolic syndrome is closely linked to overweight and obesity and a lack of physical activity.

Insulin resistance also may increase your risk for metabolic syndrome. Insulin resistance is a condition in which the body can’t use its insulin properly. Insulin is a hormone that helps move blood sugar into cells where it’s used for energy. Insulin resistance can lead to high blood sugar levels, and it’s closely linked to overweight and obesity. Genetics (ethnicity and family history) and older age are other factors that may play a role in causing metabolic syndrome.

Outlook

Metabolic syndrome is becoming more common due to a rise in obesity rates among adults. In the future, metabolic syndrome may overtake smoking as the leading risk factor for heart disease.

It is possible to prevent or delay metabolic syndrome, mainly with lifestyle changes. A healthy lifestyle is a lifelong commitment. Successfully controlling metabolic syndrome requires long-term effort and teamwork with your health care providers.

Other Names
  • Dysmetabolic syndrome
  • Hypertriglyceridemic waist
  • Insulin resistance syndrome
  • Obesity syndrome
  • Syndrome X
Causes

Metabolic syndrome has several causes that act together. You can control some of the causes, such as overweight and obesity, an inactive lifestyle, and insulin resistance.

You can't control other factors that may play a role in causing metabolic syndrome, such as growing older. Your risk for metabolic syndrome increases with age.

You also can't control genetics (ethnicity and family history), which may play a role in causing the condition. For example, genetics can increase your risk for insulin resistance, which can lead to metabolic syndrome.

People who have metabolic syndrome often have two other conditions: excessive blood clotting and constant, low-grade inflammation throughout the body. Researchers don't know whether these conditions cause metabolic syndrome or worsen it.

Researchers continue to study conditions that may play a role in metabolic syndrome, such as:

  • A fatty liver (excess triglycerides and other fats in the liver)
  • Polycystic ovarian syndrome (a tendency to develop cysts on the ovaries)
  • Gallstones
  • Breathing problems during sleep (such as sleep apnea)
Risk Factors

People at greatest risk for metabolic syndrome have these underlying causes:

  • Abdominal obesity (a large waistline)
  • An inactive lifestyle
  • Insulin resistance

Some people are at risk for metabolic syndrome because they take medicines that cause weight gain or changes in blood pressure, blood cholesterol, and blood sugar levels. These medicines most often are used to treat inflammation, allergies, HIV, and depression and other types of mental illness.

Populations Affected

Some racial and ethnic groups in the United States are at higher risk for metabolic syndrome than others. Mexican Americans have the highest rate of metabolic syndrome, followed by whites and blacks.

Other groups at increased risk for metabolic syndrome include:

  • People who have a personal history of diabetes
  • People who have a sibling or parent who has diabetes
  • Women when compared with men
  • Women who have a personal history of polycystic ovarian syndrome (a tendency to develop cysts on the ovaries)

Heart Disease Risk

Metabolic syndrome increases your risk for coronary heart disease. Other risk factors, besides metabolic syndrome, also increase your risk for heart disease. For example, a high LDL (“bad”) cholesterol level and smoking are major risk factors for heart disease. For details about all of the risk factors for heart disease, go to the Coronary Heart Disease Risk Factors Health Topic.

Even if you don’t have metabolic syndrome, you should find out your short-term risk for heart disease. The National Cholesterol Education Program (NCEP) divides short-term heart disease risk into four categories. Your risk category depends on which risk factors you have and how many you have.

Your risk factors are used to calculate your 10-year risk of developing heart disease. The NCEP has an online calculator that you can use to estimate your 10-year risk of having a heart attack.

  • High risk: You’re in this category if you already have heart disease or diabetes, or if your 10-year risk score is more than 20 percent.
  • Moderately high risk: You’re in this category if you have two or more risk factors and your 10-year risk score is 10 percent to 20 percent.
  • Moderate risk: You’re in this category if you have two or more risk factors and your 10-year risk score is less than 10 percent.
  • Lower risk: You’re in this category if you have zero or one risk factor.

Even if your 10-year risk score isn’t high, metabolic syndrome will increase your risk for coronary heart disease over time.

Screening and Prevention

 

The best way to prevent metabolic syndrom is to adopt heart-healthy lifestyle changes. Make sure to schedule routine doctor visits to keep track of your cholesterol, blood pressure, and blood sugar levels. Speak with your doctor about a blood test called a lipoprotein panel, which shows your levels of total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides.

Signs, Symptoms, and Complications

Metabolic syndrome is a group of risk factors that raises your risk for heart disease and other health problems, such as diabetes and stroke. These risk factors can increase your risk for health problems even if they're only moderately raised (borderline-high risk factors).

Most of the metabolic risk factors have no signs or symptoms, although a large waistline is a visible sign.

Some people may have symptoms of high blood sugar if diabetes—especially type 2 diabetes—is present. Symptoms of high blood sugar often include increased thirst; increased urination, especially at night; fatigue (tiredness); and blurred vision.

High blood pressure usually has no signs or symptoms. However, some people in the early stages of high blood pressure may have dull headaches, dizzy spells, or more nosebleeds than usual.

Diagnosis

Your doctor will diagnose metabolic syndrome based on the results of a physical exam and blood tests. You must have at least three of the five metabolic risk factors to be diagnosed with metabolic syndrome.

Metabolic Risk Factors

A Large Waistline

Having a large waistline means that you carry excess weight around your waist (abdominal obesity). This is also called having an "apple-shaped" figure. Your doctor will measure your waist to find out whether you have a large waistline.

A waist measurement of 35 inches or more for women or 40 inches or more for men is a metabolic risk factor. A large waistline means you're at increased risk for heart disease and other health problems.

A High Triglyceride Level

Triglycerides are a type of fat found in the blood. A triglyceride level of 150 mg/dL or higher (or being on medicine to treat high triglycerides) is a metabolic risk factor. (The mg/dL is milligrams per deciliter—the units used to measure triglycerides, cholesterol, and blood sugar.)

A Low HDL Cholesterol Level

HDL cholesterol sometimes is called "good" cholesterol. This is because it helps remove cholesterol from your arteries.

An HDL cholesterol level of less than 50 mg/dL for women and less than 40 mg/dL for men (or being on medicine to treat low HDL cholesterol) is a metabolic risk factor.

High Blood Pressure

A blood pressure of 130/85 mmHg or higher (or being on medicine to treat high blood pressure) is a metabolic risk factor. (The mmHg is millimeters of mercury—the units used to measure blood pressure.)

If only one of your two blood pressure numbers is high, you're still at risk for metabolic syndrome.

High Fasting Blood Sugar

A normal fasting blood sugar level is less than 100 mg/dL. A fasting blood sugar level between 100–125 mg/dL is considered prediabetes. A fasting blood sugar level of 126 mg/dL or higher is considered diabetes.

A fasting blood sugar level of 100 mg/dL or higher (or being on medicine to treat high blood sugar) is a metabolic risk factor.

About 85 percent of people who have type 2 diabetes—the most common type of diabetes—also have metabolic syndrome. These people have a much higher risk for heart disease than the 15 percent of people who have type 2 diabetes without metabolic syndrome.

Treatment

Heart-healthy lifestyle changes are the first line of treatment for metabolic syndrome. If heart-healthy lifestyle changes aren’t enough, your doctor may prescribe medicines. Medicines are used to treat and control risk factors, such as high blood pressure, high triglycerides, low HDL (“good”) cholesterol, and high blood sugar.

Goals of Treatment

The major goal of treating metabolic syndrome is to reduce the risk of coronary heart disease. Treatment is directed first at lowering LDL cholesterol and high blood pressure and managing diabetes (if these conditions are present).

The second goal of treatment is to prevent the onset of type 2 diabetes, if it hasn’t already developed. Long-term complications of diabetes often include heart and kidney disease, vision loss, and foot or leg amputation. If diabetes is present, the goal of treatment is to reduce your risk for heart disease by controlling all of your risk factors.

Heart-Healthy Lifestyle Changes 

Heart-healthy lifestyle changes include heart-healthy eating, aiming for a healthy weightmanaging stressphysical activity, and quitting smoking.  

Medicines

Sometimes lifestyle changes aren’t enough to control your risk factors for metabolic syndrome.  For example, you may need statin medications to control or lower your cholesterol. By lowering your blood cholesterol level, you can decrease your chance of having a heart attack or stroke. Doctors usually prescribe statins for people who have:

  • Diabetes
  • Heart disease or had a prior stroke
  • High LDL cholesterol levels

Doctors may discuss beginning statin treatment with those who have an elevated risk for developing heart disease or having a stroke.

Your doctor also may prescribe other medications to:

  • Decrease your chance of having a heart attack or dying suddenly.
  • Lower your blood pressure.
  • Prevent blood clots, which can lead to heart attack or stroke.
  • Reduce your heart’s workload and relieve symptoms of coronary heart disease.

Take all medicines regularly, as your doctor prescribes. Don’t change the amount of your medicine or skip a dose unless your doctor tells you to. You should still follow a heart-healthy lifestyle, even if you take medicines to treat your risk factors for metabolic syndrome. 

Living With

Metabolic syndrome is a lifelong condition. However, lifestyle changes can help you control your risk factors and reduce your risk for coronary heart disease and diabetes.

If you already have heart disease or diabetes, lifestyle changes can help you prevent or delay related problems. Examples of these problems include heart attack, stroke, and diabetes-related complications (for example, damage to your eyes, nerves, kidneys, feet, and legs).

Heart-healthy lifestyle changes may include:

If lifestyle changes aren’t enough, your doctor may recommend medicines. Take all of your medicines as prescribed by your doctor. Make realistic short- and long-term goals for yourself when you begin to make healthy lifestyle changes. Work closely with your doctor, and seek regular medical care.

Participate in NHLBI Clinical Trials

The National Heart, Lung, and Blood Institute (NHLBI) leads or sponsors many studies aimed at preventing, diagnosing, and treating heart, lung, blood, and sleep disorders.

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