What is it?
Metabolic syndrome is a cluster of conditions — increased blood pressure, elevated insulin levels, excess body fat around the waist or abnormal cholesterol levels — that occur together, increasing your risk of heart disease, stroke and diabetes.
Having just one of these conditions isn't diagnosed as metabolic syndrome, but it does contribute to your risk of serious disease. If more than one of these conditions occur in combination, your risk is even greater.
If you have metabolic syndrome or any of the components of metabolic syndrome, aggressive lifestyle changes can delay or even prevent the development of serious health problems.
Having metabolic syndrome means you have three or more disorders related to your metabolism at the same time, including:
- Obesity, particularly around your waist (having an "apple shape")
- A systolic (top number) blood pressure measurement higher than 120 millimeters of mercury (mm Hg) or a diastolic (bottom number) blood pressure measurement higher than 80 mm Hg
- An elevated level of the blood fat called triglycerides and a low level of high-density lipoprotein (HDL) cholesterol — the "good" cholesterol
- Resistance to insulin, a hormone that helps to regulate the amount of sugar in your body
Having one component of metabolic syndrome means you're more likely to have others. And the more components you have, the greater are the risks to your health.
Metabolic syndrome is linked to your body's metabolism, possibly to a condition called insulin resistance. Insulin is a hormone made by your pancreas that helps control the amount of sugar in your bloodstream.
Normally, your digestive system breaks down the foods you eat into sugar (glucose). Your blood carries the glucose to your body's tissues, where the cells use it as fuel. Glucose enters your cells with the help of insulin. In people with insulin resistance, cells don't respond normally to insulin, and glucose can't enter the cells as easily. Your body reacts by churning out more and more insulin to help glucose get into your cells. The result is higher than normal levels of insulin in your blood. This can eventually lead to diabetes when your body is unable to make enough insulin to control the blood glucose to the normal range.
Even if your levels aren't high enough to be considered diabetes, an elevated glucose level can still be harmful. In fact, some doctors refer to this condition as "prediabetes." Increased insulin raises your triglyceride level and other blood fat levels. It also interferes with how your kidneys work, leading to higher blood pressure. These combined effects of insulin resistance put you at risk of heart disease, stroke, diabetes and other conditions.
Combination of factors
Researchers are still learning what causes insulin resistance. It probably involves a variety of genetic and environmental factors. Some people may be genetically prone to insulin resistance, inheriting the tendency from their parents. But being overweight and inactive are major contributors.
Disagreement among experts
Not all experts agree on the definition of metabolic syndrome or whether it even exists as a distinct medical condition. Doctors have talked about this cluster of risk factors for years and have called it many names, including syndrome X and insulin resistance syndrome.
The following factors increase your chances of having metabolic syndrome:
- Age. The risk of metabolic syndrome increases with age, affecting less than 10 percent of people in their 20s and 40 percent of people in their 60s. However, warning signs of metabolic syndrome can appear in childhood.
- Race. Hispanics and Asians seem to be at greater risk of metabolic syndrome than other races are.
- Obesity. A body mass index (BMI) — a measure of your percentage of body fat based on height and weight — greater than 25 increases your risk of metabolic syndrome. So does abdominal obesity — having an apple shape rather than a pear shape.
- History of diabetes. You're more likely to have metabolic syndrome if you have a family history of type 2 diabetes or a history of diabetes during pregnancy (gestational diabetes).
- Other diseases. A diagnosis of high blood pressure, cardiovascular disease or polycystic ovary syndrome — a similar type of metabolic problem that affects a woman's hormones and reproductive system — also increases your risk of metabolic syndrome.
Having metabolic syndrome can increase your risk of developing these conditions:
- Diabetes. If you don't make lifestyle changes to control your insulin resistance, your glucose levels will continue to increase. You may develop diabetes as a result of metabolic syndrome.
- Cardiovascular disease. High cholesterol and high blood pressure can contribute to the buildup of plaques in your arteries. These plaques can cause your arteries to narrow and harden, which can lead to a heart attack or stroke.
Although your doctor is not typically looking for metabolic syndrome, the label may apply if you have three or more of the traits associated with this condition.
Several organizations have criteria for diagnosing metabolic syndrome. These guidelines were created by the National Cholesterol Education Program (NCEP) with modifications by the American Heart Association. According to these guidelines, you have metabolic syndrome if you have three or more of these traits:
- Large waist circumference, greater than 35 inches (89 centimeters, or cm) for women and 40 inches (102 cm) for men. Certain genetic risk factors, such as having a family history of diabetes or being of Asian descent — which increases your risk of insulin resistance — lower the waist circumference limit. If you have one of these genetic risk factors, waist circumference limits are 31 to 35 inches (79 to 89 cm) for women and 37 to 39 inches (94 to 99 cm) for men.
- A triglyceride level higher than 150 milligrams per deciliter (mg/dL), or 1.7 millimoles per liter (mmol/L), or you're receiving treatment for high triglycerides.
- Reduced HDL ("good") cholesterol — less than 40 mg/dL (1 mmol/L) in men or less than 50 mg/dL (1.3 mmol/L) in women — or you're receiving treatment for low HDL.
- Blood pressure higher than 120 millimeters of mercury (mm Hg) systolic or higher than 80 mm Hg diastolic, or you're receiving treatment for high blood pressure.
- Elevated fasting blood sugar (blood glucose) of 100 mg/dL (5.6 mmol/L) or higher, or you're receiving treatment for high blood sugar.