What is the metabolic syndrome?

The metabolic syndrome is characterized by a group of metabolic risk factors in one person. They include:

• Abdominal obesity (excessive fat tissue in and around the abdomen)
• Atherogenic dyslipidemia (blood fat disorders — high triglycerides, low HDL cholesterol and high LDL cholesterol — that foster plaque buildups in artery walls)
• Elevated blood pressure
• Insulin resistance or glucose intolerance (the body can’t properly use insulin or blood sugar)
• Prothrombotic state (e.g., high fibrinogen or plasminogen activator inhibitor–1 in the blood)
• Proinflammatory state (e.g., elevated C-reactive protein in the blood)

People with the metabolic syndrome are at increased risk of coronary heart disease and other diseases related to plaque buildups in artery walls (e.g., stroke and peripheral vascular disease) and type 2 diabetes. The metabolic syndrome has become increasingly common in the United States. It’s estimated that over 50 million Americans have it.

The dominant underlying risk factors for this syndrome appear to be abdominal obesity and insulin resistance. Insulin resistance is a generalized metabolic disorder, in which the body can’t use insulin efficiently. This is why the metabolic syndrome is also called the insulin resistance syndrome.

Other conditions associated with the syndrome include physical inactivity, aging, hormonal imbalance and genetic predisposition.

Some people are genetically predisposed to insulin resistance. Acquired factors, such as excess body fat and physical inactivity, can elicit insulin resistance and the metabolic syndrome in these people. Most people with insulin resistance have abdominal obesity. The biologic mechanisms at the molecular level between insulin resistance and metabolic risk factors aren’t fully understood and appear to be complex.

How is the metabolic syndrome diagnosed?
There are no well-accepted criteria for diagnosing the metabolic syndrome. The criteria proposed by the National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III), with minor modifications, are currently recommended and widely used.

The American Heart Association and the National Heart, Lung, and Blood Institute recommend that the metabolic syndrome be identified as the presence of three or more of these components:

• Elevated waist circumference:
  Men — Equal to or greater than 40 inches (102 cm)
  Women — Equal to or greater than 35 inches (88 cm)
• Elevated triglycerides:
  Equal to or greater than 150 mg/dL
• Reduced HDL (“good”) cholesterol:
  Men — Less than 40 mg/dL
  Women — Less than 50 mg/dL
• Elevated blood pressure:
  Equal to or greater than 130/85 mm Hg
• Elevated fasting glucose:
  Equal to or greater than 100 mg/dL

AHA Recommendation for Managing the Metabolic Syndrome:
The primary goal of clinical management of the metabolic syndrome is to reduce the risk for cardiovascular disease and type 2 diabetes. Then, the first-line therapy is to reduce the major risk factors for cardiovascular disease: stop smoking and reduce LDL cholesterol, blood pressure and glucose levels to the recommended levels.

For managing both long- and short-term risk, lifestyle therapies are the first-line interventions to reduce the metabolic risk factors. These lifestyle interventions include:

• Weight loss to achieve a desirable weight (BMI less than 25 kg/m²)
• Increased physical activity, with a goal of at least 30 minutes of moderate-intensity activity on most days of the week 
• Healthy eating habits that include reduced intake of saturated fat, trans fat and cholesterol