What is metabolic syndrome?
Metabolic syndrome is a cluster of metabolic risk factors that come together in a single individual. These metabolic factors include insulin resistance, hypertension (high blood pressure), cholesterol abnormalities, and an increased risk for blood clotting. Affected individuals are most often overweight or obese. An association between certain metabolic disorders and cardiovascular disease has been known since the 1940s.
Metabolic syndrome is considered to be a risk factor for cardiovascular diseases and type 2 diabetes. Insulin resistance refers to the diminished ability of cells to respond to the action of insulin in promoting the transport of the sugar glucose, from blood into muscles and other tissues. Type 2 diabetes is caused by insulin resistance.
Metabolic syndrome is also known as syndrome X, insulin resistance syndrome, or dysmetabolic syndrome.
How is metabolic syndrome defined?
Based on the guidelines from the National Heart, Lung, and Blood Institute (NHLBI) and the American Heart Association (AHA), any three of the following traits in the same individual meet the criteria for the metabolic syndrome:
- Abdominal obesity: a waist circumference of 102 cm (40 in) or more in men and 88 cm (35 inches) or more in women. For Asian Americans, the cutoff values are ≥90 cm (35 in) in men or ≥80 cm (32 in) in women
Serum triglycerides 150 mg/dl or above.
- HDL cholesterol 40mg/dl or lower in men and 50mg/dl or lower in women.
- Blood pressure of 130/85 or more.
- Fasting blood glucose of 100 mg/dl or above.
Metabolic Syndrome Symptoms
Metabolic syndrome is a group of risk factors that raises your risk for heart disease and other health problems, such as diabetesexternal link icon 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.
National Heart Lung and Blood Institute. What Are the Signs and Symptoms of Metabolic Syndrome?
How common is metabolic syndrome?
Metabolic syndrome is quite common. Approximately 32% of the population in the U.S. has metabolic syndrome,
and about 85% of those with type 2 diabetes have metabolic syndrome. Around 25% of adults in Europe and Latin America are estimated to have the condition, and rates are rising in developing East Asian countries. Within the US, Mexican Americans have the highest prevalence of metabolic syndrome. The prevalence of metabolic syndrome increases with age, and about 40% of people over 60 are affected.
What causes, and what are the risk factors of metabolic syndrome?
As is true with many medical conditions, genetics and the environment both play important roles in the development of the metabolic syndrome.
Genetic factors influence each individual component of the syndrome, and the syndrome itself. A family history that includes type 2 diabetes, hypertension, and early heart disease greatly increases the chance that an individual will develop the metabolic syndrome.
Environmental issues such as low activity level, sedentary lifestyle, and progressive weight gain also contribute significantly to the risk of developing the metabolic syndrome.
Metabolic syndrome is present in about 5% of people with normal body weight, 22% of those who are overweight and 60% of those considered obese. Adults who continue to gain five or more pounds per year raise their risk of developing metabolic syndrome by up to 45%.
While obesity itself is likely the greatest risk factor, others factors of concern include:
- Post-menopausal women
- Eating an excessively high carbohydrate diet
- Sedentary lifestyle
What are the symptoms of metabolic syndrome?
Metabolic syndrome is a condition that in general, has no symptoms. If a person has risk factors for metabolic syndrome (particularly a large waist circumference), your doctor can help evaluate your risk.
Why should I know about metabolic syndrome?
Metabolic syndrome is worth caring about because it is significant risk factor for the development of both type 2 diabetes and heart disease, two of the most common and important chronic diseases today.
- Metabolic syndrome is associated with fat accumulation in the liver (fatty liver), resulting in inflammation and the potential for cirrhosis.
- The kidneys can also be affected, as there is an association with microalbuminuria -- the leaking of protein into the urine, a subtle but clear indication of kidney damage.
- Other problems associated with metabolic syndrome include obstructive sleep apnea, polycystic ovary syndrome, increased risk of dementia with aging, and cognitive decline in the elderly.
What is the treatment for metabolic syndrome?
The major goals are to treat both the underlying cause
of the syndrome, to prevent the development of type 2 diabetes, and also to treat the cardiovascular risk factors if they persist. As has been
discussed, a majority of people with metabolic syndrome are overweight and
live a sedentary lifestyle.
Lifestyle modification is the preferred treatment of metabolic syndrome.
Weight reduction usually requires a specifically tailored multifaceted program
that includes diet and exercise.
Smoking cessation is an important component of treatment, and sometimes medications may be useful.
Diet and metabolic syndrome
A detailed discussion of diet therapies, pros and cons of various diets etc.
is beyond the scope of this article. However, there is now a trend toward the
use of a Mediterranean diet -- one that is rich in
"good" fats (olive oil) and contains a
reasonable amount of carbohydrates and proteins (such as from fish
The Mediterranean diet is palatable and easily sustained. In addition, recent
studies have shown that when compared to a low fat diet, people on the
Mediterranean diet have a greater decrease in body weight, and also had greater
improvements in blood pressure, cholesterol levels, and other markers of heart
disease -- all of which are important in evaluating and treating metabolic
Other nutritional plans that may be recommended for people with metabolic
syndrome include the American Dietary Association (ADA) diet and the
Dietary Approaches to Stop Hypertension (DASH) diet.
Exercise and metabolic syndrome
A sustainable exercise program, for example 30 minutes
five days a week is reasonable to start, providing there is no medical
contraindication. (If you have any special concerns in this regard, check with
your doctor first.) There is a beneficial effect of exercise on blood pressure,
cholesterol levels, and insulin sensitivity, regardless of whether weight loss is achieved or not. Thus,
exercise in itself is a helpful tool in treating metabolic syndrome.
Cosmetic surgery to remove fat
Some people may ask: Why not just have liposuction of the abdomen and remove the large amount of abdominal fat that is a big part of the problem? Data thus far shows no benefit in liposuction on insulin sensitivity, blood pressure, or cholesterol. As the saying goes, "If it's too good to be true, it probably is." Diet and exercise are still the preferred primary treatment of metabolic syndrome.
What if lifestyle changes are not enough to treat metabolic syndrome?
What if changes in lifestyle do not do the trick, what then? Drugs to control cholesterol levels, lipids, and high blood pressure may be considered.
If someone has already had a heart attack, their LDL ("bad") cholesterol should be reduced below 70mg/dl. A person who has diabetes has a heart attack risk equivalent to that of someone who has already one and so should be treated in the same way. If you have metabolic syndrome, a detailed discussion about lipid therapy is needed between you and your doctor, as each individual is unique.
Blood pressure goals are generally set lower than 130/80. Some blood pressure
medications offer more benefits than simply lowering blood pressure. For example, a class
of blood pressure drugs called ACE inhibitors has been found to also reduce the
levels of insulin resistance and actually deter the development of type 2
diabetes. This is an important consideration when discussing the choice blood
pressure drugs in the metabolic syndrome.
The discovery that a drug is prescribed for one condition, and has other
beneficial effects is not new. Drugs used to treat high blood sugar
and insulin resistance may have beneficial effects on blood pressure and
usually used to treat type 2 diabetes, also has been found to help prevent the
onset of diabetes in people with metabolic syndrome. However, there are currently
no established guidelines on treating metabolic syndrome patients with metformin
if they do not have overt diabetes.
Metabolic Syndrome Summary
Choosing healthier lifestyles such as exercising; losing weight; lowering blood pressure, cholesterol and triglyceride levels may decrease a person's chance of developing metabolic syndrome.
The final take home message is make healthy lifestyle changes. Some suggestions for doing this are:
- Invite a buddy to exercise with you.
- Take a walk during your work break, even if it is just around the building.
- Increase consumption of fruits and vegetables and decrease consumption of fats.
- Grocery shop at healthy food stores.
- Evaluate what you feed your kids.
- Urge children to go outside and play.
It all adds up. Preventing metabolic syndrome really means having a healthy lifestyle.
Medically reviewed by a Board-Certified Family Practice Physician
American Heart Association. Symptoms and Diagnosis of Metabolic Syndrome.
Medscape. Metabolic Syndrome.
NIH. What Is Metabolic Syndrome?