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Metabolic Syndrome

(Syndrome X; Insulin Resistance Syndrome)


Adrienne Youdim

, MD, David Geffen School of Medicine at UCLA

Last full review/revision Jun 2020| Content last modified Jun 2020
Click here for the Professional Version

Metabolic syndrome is characterized by a large waist circumference (due to excess abdominal fat), high blood pressure, resistance to the effects of insulin (insulin resistance) or diabetes, and abnormal levels of cholesterol and other fats in the blood (dyslipidemia).

  • Excess abdominal fat increases the risk of high blood pressure, coronary artery disease, and type 2 diabetes.

  • To diagnose metabolic syndrome, doctors measure waist circumference, blood pressure, and fasting blood sugar and fat (lipid) levels.

  • Exercise, changes in eating habits, behavioral techniques, and drugs may be used to help people lose weight.

  • Diabetes, high blood pressure, and abnormal blood cholesterol and fat levels are treated.

In developed countries, metabolic syndrome is a serious problem. In the United States, more than 40% of people over 50 may have it. Even children and adolescents can develop metabolic syndrome, but how many have it is unknown.

Metabolic syndrome is more likely to develop when people store excess fat in the abdomen (apple-shaped) rather than around the hips (pear-shaped). The following people tend to store excess fat in the abdomen:

  • Most men

  • Women after menopause

Storing excess fat in the abdomen increases the risk of the following:

Metabolic syndrome itself causes no symptoms.

(See also Obesity.)

Diagnosis of Metabolic Syndrome

  • Waist circumference

  • Blood pressure measurement

  • Blood tests to measure sugar and fat (lipid) levels

Waist circumference should be measured in all people because even people who are not overweight or appear lean can store excess fat in the abdomen. The greater the waist circumference, the higher the risk of metabolic syndrome and its complications. Risk is substantially increased if waist circumference is more than the following:

  • 31 inches (79 centimeters) in white women

  • 28 inches (72 centimeters) in Asian Indian women

  • 37 inches (93 centimeters) in white men

  • 30.7 inches (78 centimeters) in Asian Indian men

If waist circumference is high, doctors should measure blood pressure and blood sugar and fat levels after fasting. Levels of both blood sugar and fats are often abnormal.

Metabolic syndrome is diagnosed when the waist circumference is 40 inches (102 centimeters) or more in men or 35 inches (88 centimeters) or more in women (indicating excess fat in the abdomen) and when people have or are being treated for two or more of the following:

  • A fasting blood sugar level of 100 mg/dL (milligrams per deciliter) or higher

  • Blood pressure of 130/85 mm Hg (millimeters of mercury) or higher

  • A fasting blood triglyceride (a fat) level of 150 mg/dL or higher

  • A high density lipoprotein (HDL—the good) cholesterol level of less than 40 mg/dL for men or less than 50 mg/dL for women

Treatment of Metabolic Syndrome

  • Exercise and changes in eating habits

  • Treatment of high blood sugar, high blood pressure, and abnormal fat levels

  • Sometimes metformin

The initial treatment involves exercise and changes in eating habits. Each part of metabolic syndrome should also be treated with drugs if necessary.

If people have diabetes or a high blood sugar level, drugs that increase the body’s sensitivity to insulin, such as metformin or a thiazolidinedione drug (for example, rosiglitazone or pioglitazone), may help. Also, exercise is important for people with diabetes because it enables the body to use blood sugar more efficiently and can often help lower the blood sugar level.

High blood pressure and abnormal fat levels in blood are also treated. Drugs to lower blood pressure (antihypertensives) or to lower lipid levels are used if needed.

Other risk factors for coronary artery disease, if present, should be controlled. For example, smokers are advised to stop smoking.

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