What is metabolic syndrome?
Metabolic syndrome refers to the presence of a cluster of risk factors specific for cardiovascular disease. Metabolic syndrome greatly raises the risk of developing diabetes, heart disease, stroke, or all three.
According to the National Heart, Lung and Blood Institute (NHLBI), the cluster of metabolic factors involved includes:
- Abdominal obesity. This means having a waist circumference of more than 35 inches for women and more than 40 inches for men. An increased waist circumference is the form of obesity most strongly tied to metabolic syndrome.
- High blood pressure of 130/80 mm Hg (millimeters of mercury) or higher. Normal blood pressure is defined as less than 120 mm Hg for systolic pressure (the top number), and less than 80 mm Hg for diastolic pressure (the bottom number). High blood pressure is strongly tied to obesity. It is often found in people with insulin resistance.
- Impaired fasting blood glucose. This means a level equal to or greater than 100 mg/dL
- High triglyceride levels of more than 150 mg/dL. Triglycerides are a type of fat in the blood.
- Low HDL (good) cholesterol. Less than 40 mg/dL for men and less than 50 mg/dL for women is considered low.
The NHLBI and AHA recommend a diagnosis of metabolic syndrome when a person has 3 or more of these factors.
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 people with metabolic syndrome, makes it more difficult for cells in the body to respond to insulin. If the body can’t make enough insulin to override the resistance, the blood sugar level increases, causing type 2 diabetes. Metabolic syndrome may be a start of the development of type 2 diabetes.
What causes metabolic syndrome?
Experts don’t fully understand what causes metabolic syndrome. Several factors are interconnected. Obesity plus a sedentary lifestyle contributes to risk factors for metabolic syndrome. These include 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 tied, many healthcare providers believe that insulin resistance may be a cause of metabolic syndrome. But they have not found a direct link between the two conditions. Others believe that hormone changes caused by chronic stress lead to abdominal obesity, insulin resistance, and higher blood lipids (triglycerides and cholesterol).
Other factors that may contribute to metabolic syndrome include genetic changes in a person’s ability to break down fats (lipids) in the blood, older age, and problems in how body fat is distributed.
Who is at risk for metabolic syndrome?
Knowing your risk factors for any disease can help guide you to take the appropriate actions. This includes changing behaviors and being monitored by your healthcare provider for the disease.
Risk factors most closely tied to metabolic syndrome include:
- Age. You are more likely to have metabolic syndrome the older you are.
- Ethnicity. African Americans and Mexican Americans are more likely to get metabolic syndrome. African-American women are about 60% more likely than African-American men to have the syndrome.
- Body mass index (BMI) greater than 25. The BMI is a measure of body fat compared with height and weight.
- Personal or family history of diabetes. Women who have had diabetes during pregnancy (gestational diabetes) or people who have a family member with type 2 diabetes are at greater risk for metabolic syndrome.
- History of heavy drinking
- Being past menopause
- High-fat diet
- Sedentary lifestyle
What are the symptoms of metabolic syndrome?
Having high blood pressure, high triglycerides, and being overweight or obese may be signs of metabolic syndrome. People with insulin resistance may have acanthosis nigricans. This is darkened skin areas on the back of the neck, in the armpits, and under the breasts. In general, people do not have symptoms.
The symptoms of metabolic syndrome may look like other health conditions. See your healthcare provider for a diagnosis.
How is metabolic syndrome diagnosed?
Expert organizations have developed criteria to diagnose metabolic syndrome. Criteria include:
- Abdominal obesity
- BMI above 25
- High triglycerides
- Low HDL cholesterol
- High blood pressure or using medicine to lower blood pressure
- High fasting blood glucose
- Increased blood clotting. This means you have more plasma plasminogen activator and fibrinogen, which cause blood to clot.
- Insulin resistance. This means you have type 2 diabetes, impaired fasting glucose, or impaired glucose tolerance. The impaired glucose tolerance test measures the body’s response to sugar.
Each organization has its own guidelines for using the above criteria to diagnose metabolic syndrome.