Metabolic Syndrome

By Julie Garner

What is metabolic syndrome?

Metabolic syndrome is a condition that includes the presence of a cluster of risk factors specific for cardiovascular disease. Metabolic syndrome significantly raises the risk of developing diabetes, heart disease, and/or stroke.

Most people who have metabolic syndrome have insulin resistance. The body makes insulin to move glucose (sugar) into cells for use as energy. Obesity, commonly found in persons with metabolic syndrome, makes it more difficult for cells to respond to insulin. If the body cannot make enough insulin to override the resistance, the blood sugar level increases and diabetes can result. Metabolic syndrome may be a beginning of the development of type 2 diabetes.

The cluster of conditions and risk factors related to metabolic syndrome was first named in 1988. Dr. Gerald Reaven proposed that insulin resistance was central to the cause of type 2 diabetes, high blood pressure, and cardiovascular artery disease. Reaven called this cluster of abnormalities "Syndrome X." Since that time, Syndrome X has come to be known by various names, including metabolic syndrome, dysmetabolic syndrome, and insulin resistance syndrome. Syndrome X is now widely known as metabolic syndrome.

The American Heart Association (AHA) recognizes metabolic syndrome as a problem of growing concern, especially for those older than 60. Research suggests that more than 47 million Americans have it. Because the population of the United States is aging and because metabolic syndrome prevalence increases with age, the AHA has estimated that metabolic syndrome soon will become the primary risk factor for cardiovascular disease, ahead of cigarette smoking. Increasing rates of obesity are also thought to be related to the increasing rates of metabolic syndrome.

The cluster of metabolic factors involved as defined by the National Cholesterol Education Program's Adult Treatment Panel III (NCEP-ATP III) report, sponsored by the National Heart, Lung, and Blood Institute (NHLBI), includes:

  • Abdominal obesity, in which the waist circumference measures more than 35 inches for women and more than 40 inches for men - an increased waist circumference is the form of obesity most strongly associated with metabolic syndrome.

  • High blood pressure of 130/85 mm Hg (millimeters of mercury) or higher -- normal blood pressure is defined as 120 mm Hg or lower for systolic pressure (the top number), and 80 mm Hg or lower for diastolic pressure (the bottom number). High blood pressure is strongly associated with obesity and is often found in persons with insulin resistance.

  • Elevated fasting blood glucose level equal to or greater than 150 MG/DL

  • High triglyceride levels of more than 150 mg/dl (milligrams per deciliter) -- triglycerides are a type of fat in the blood

  • HDL cholesterol (the "good" cholesterol) of less than 40 mg/dl for men and less than 50 mg/dl for women

The NHLBI and the AHA recommend a diagnosis of metabolic syndrome when three or more of these factors are identified.

What causes metabolic syndrome?

Because of the involvement of several interconnected factors in metabolic syndrome, the direct cause is not clearly understood. The rise in obesity, coupled with a sedentary lifestyle, contribute to risk factors for metabolic syndrome, such as high cholesterol, insulin resistance, and high blood pressure. These risk factors may lead to cardiovascular disease and type 2 diabetes.

Because metabolic syndrome and insulin resistance are closely associated, many healthcare professionals believe that insulin resistance may be a cause of metabolic syndrome. However, a direct link between the two conditions has not been established. Others believe that hormone changes, caused by chronic stress, lead to the development of abdominal obesity, insulin resistance, and elevated blood lipids (triglycerides and cholesterol).

Other factors which are thought to contribute to the development of metabolic syndrome include genetic variations in a person's ability to break down lipids (fats) in the blood, older age, and abnormalities in the distribution of body fat.