Metabolic syndrome

What is metabolic syndrome?

Metabolic syndrome is a cluster of conditions — all of which increase the risk of heart disease — occurring together in one individual. People with metabolic syndrome not only have an increased risk of heart disease, but their risk of stroke and diabetes is also higher than average. Metabolic syndrome (also known as syndrome X and the insulin resistance syndrome) affects about 20-30 per cent of the adult population in Australia.

Five major international organisations recently developed a unified definition for metabolic syndrome. To have metabolic syndrome, a person must have at least 3 of the following 5 abnormal findings:

  • central obesity (body fat that’s concentrated around the waist);
  • a raised triglyceride level (a type of fat in the blood);
  • a low level of HDL-cholesterol (‘good’ cholesterol);
  • high blood pressure; or
  • an increased blood sugar level after a period of fasting, or previously diagnosed type 2 diabetes.

If you had high blood pressure which is now normal because it’s controlled by medicine, then for the purposes of diagnosing metabolic syndrome you are still classed as having high blood pressure. Similarly, if your HDL-cholesterol or triglyceride results are normal but you’re taking medicine to make them that way, then you are still classed as having those risk factors.

The International Diabetes Federation defines central obesity in people of European descent as a waist circumference of 94 cm or more in men and 80 cm or more in women. But these values are not appropriate for all ethnic groups because of the differences in body proportions in different populations. For South and South-East Asian people, the corresponding values are 90 cm for men but remain at 80 cm for women.

Who gets metabolic syndrome?

Factors that may put you at a higher risk than other people of developing metabolic syndrome include:

  • increasing age;
  • a diet that’s high in kilojoules and saturated fat;
  • lack of exercise and physical activity;
  • a family history of diabetes;
  • a history of gestational diabetes (diabetes during pregnancy);
  • a history of polycystic ovary syndrome (a metabolic disorder that affects a woman’s hormones and reproductive system); and
  • being of Asian descent.

Although metabolic syndrome generally affects older people, it is possible, with increasing childhood obesity, for metabolic syndrome to affect young adults and even adolescents and children.

What causes metabolic syndrome?

It is thought that the underlying causes of metabolic syndrome are central obesity (weight that is carried mainly around the waist) and resistance to insulin (a hormone made by the pancreas that helps control your blood sugar levels).

People who have insulin resistance tend to have higher than normal levels of insulin and sugar in their blood, increasing the risk of diabetes. In addition, high levels of insulin can contribute to the development of high blood pressure and help raise triglyceride levels.

The cause of insulin resistance is not yet properly understood, but both genetic and environmental factors, including being overweight and physically inactive, are thought to play a major role.

Why is metabolic syndrome a health concern?

All of the individual components of metabolic syndrome are risk factors for atherosclerosis (hardening and narrowing of the arteries). Atherosclerosis causes coronary heart disease (the disease that’s responsible for angina and heart attacks) and strokes. People with metabolic syndrome, who have a combination of several of these risk factors rolled into one, are at even higher risk of these problems. Having metabolic syndrome doubles your risk of having cardiovascular disease, such as heart attack or stroke, compared with people who don’t have this syndrome.

Insulin resistance and central obesity also put you at high risk of developing diabetes — people with metabolic syndrome have 5 times the risk of developing type 2 diabetes.

Is there any treatment?

Lifestyle interventions are the first step in treating metabolic syndrome. By changing your lifestyle, you can help delay or even prevent the complications of metabolic syndrome (heart disease, stroke and diabetes) from developing.

Lose weight

Even a small amount of weight loss can help improve insulin resistance, lower your blood pressure and correct your cholesterol levels. Try to restrict your calorie intake to achieve a 5-10 per cent reduction in your body weight within 12 months.

Eat a healthy diet

A healthy diet is one that’s low in kilojoules, fat and salt, and high in whole grains, fruits and vegetables. Reducing the amount of fats, especially saturated fats and trans fats, in your diet not only helps with weight loss, but also improves cholesterol levels. A healthy diet can also reduce your risk of developing diabetes, and by reducing your salt intake and eating healthily you can reduce your blood pressure.

Get physical

Try to fit in 30-60 minutes of moderately strenuous activity (such as a brisk walk) on most days of the week. Increasing your level of physical activity will help you lose weight, lower your blood pressure and improve your blood glucose and cholesterol levels. But remember, if you don’t usually get much physical activity, it’s best to check with your doctor before starting an exercise programme.

Stop smoking

Smoking worsens the health problems associated with metabolic syndrome. By quitting smoking you can help reduce your risk of heart disease and diabetes.

It’s important to have regular check-ups with your doctor to measure your weight, waist circumference, cholesterol levels, blood pressure and blood sugar levels. Your doctor can also provide support and help you stay motivated to keep up with your new, healthier habits.

What about medicines?

When lifestyle modifications alone aren't enough, medicines can be used to lower blood pressure and correct cholesterol and triglyceride levels. Medicines that control blood sugar levels can be used to treat people who already have type 2 diabetes, and also those with insulin resistance and elevated blood sugar levels, to delay or prevent the onset of full-blown diabetes.

There are also medicines available that can help with weight loss, which may be effective for some people when used in combination with a balanced diet and exercise. Medicines for weight loss are generally only tried if diet and exercise alone have not been successful.

Your doctor may also recommend you take low-dose aspirin, which has been found to reduce the risk of heart attack and stroke when taken on a daily basis.

Last Reviewed: 5 February 2010
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References

1. Alberti KGMM, Eckel RH, Grundy SM, et al. Harmonizing the metabolic syndrome: A Joint Interim Statement of the International Diabetes Federation Task Force on Epidemiology and Prevention; National Heart, Lung, and Blood Institute; American Heart Association; World Heart Federation; International Atherosclerosis Society; and International Association for the Study of Obesity. Circulation 2009; 120: 1640-45.
2. Eckel RH, Alberti KGMM, Grundy SM, Zimmett PZ. The metabolic syndrome. Lancet 2010; 375: 181-83.
3. National Heart Lung and Blood Institute. What is the metabolic syndrome? [Website; revised January 2010]. http://www.nhlbi.nih.gov/health/dci/Diseases/ms/ms_whatis.html (accessed February 2010).
4. American Heart Association. Statistical fact sheet risk factors. Metabolic syndrome statistics [Updated 2010]. Available from: http://www.americanheart.org/downloadable/heart/1136819875357META06.pdf (accessed February 2010).
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