Diseases & Conditions


Metabolic Syndrome

Metabolic syndrome (also called syndrome X or insulin resistance syndrome) is characterized by excess abdominal fat, resistance to the effects of insulin (insulin resistance), abnormal levels of fats in the blood, and high blood pressure. Excess abdominal fat increases the risk of high blood pressure, coronary artery disease, and type 2 diabetes. Doctors measure waist circumference, blood pressure, and fasting blood sugar and fat (lipid) levels. Changes in eating habits, exercise, behavioral techniques, and drugs may be used to help people lose weight. Diabetes, high blood pressure, and abnormal 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 around 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: Coronary artery disease High blood pressure Type 2 diabetes Abnormal levels of fats (lipids), including cholesterol, in the blood (dyslipidemia) Fatty liver Gout Polycystic ovary syndrome (in women) Chronic kidney disease

Metabolic syndrome itself causes no symptoms.


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 (80 centimeters) in white or Asian women 37 inches (94 centimeters) in white men 33 inches (85 centimeters) in Asian men

If waist circumference is high, doctors should measure blood pressure and blood sugar and fat levels after fasting. These levels are often both abnormal. The metabolic syndrome is diagnosed when the waist circumference is more than 40 inches (102 centimeters) in men or more than 35 inches (88 centimeters) 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 more than 100 mg/dL (milligrams per deciliter) Blood pressure of more than 130/80 mm Hg (millimeters of mercury) A fasting blood triglyceride (a fat) level of more than 150 mg/dL A high density lipoprotein (HDL—the good) cholesterol level of 40 mg/dL or less for men or 50 mg/dL or less for women


The initial treatment involves changes in diet and exercise. Each part of the 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 Some Trade Names GLUCOPHAGE or a thiazolidinedione drug (for example, rosiglitazone Some Trade Names AVANDIA or pioglitazone Some Trade Names ACTOS ), 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.

Last full review/revision August 2008 by Adrienne Youdim, MD

Source: The Merck Manual Home Edition