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22 November, 2009

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Metabolic syndrome

Metabolic syndrome is a collection of disorders that occur together and increase your risk of developing type 2 diabetes, stroke or heart disease. The causes of metabolic syndrome are complex and not well understood, but there is thought to be a genetic link. Being overweight or obese and physically inactive adds to your risk. Metabolic syndrome is sometimes called syndrome X or insulin resistance syndrome.

As we get older, we tend to become less active and may gain excess weight. This weight is generally stored around the abdomen. This can lead to the body becoming resistant to the hormone insulin. This means that insulin in the body is less effective, especially in the muscles and liver.

More than 25 per cent of Australian adults have metabolic syndrome. This is higher in people with diabetes.

A group of conditions that occur together
Metabolic syndrome is not a disease in itself but a collection of disorders that occur together. A person is classed as having metabolic syndrome when they have:

Central (abdominal) obesity – excess fat in and around the stomach (abdomen) - plus any two of the following factors:
- Raised blood pressure (hypertension)
- High blood triglycerides
Low levels of high density lipoproteins (HDL) – the ‘good’ cholesterol
Impaired fasting glucose (IFG) – blood glucose levels are higher than normal but not high enough to be diagnosed as type 2 diabetes.

Insulin resistance
Insulin resistance means that your body does not use the hormone insulin as effectively as it should, especially in the muscles and liver.

Normally your digestive system breaks down carbohydrates into glucose, which then passes from your intestine into your bloodstream. As your blood glucose level rises, your pancreas secretes insulin into your bloodstream. Insulin allows glucose to move into your muscle cells from your blood. Once inside a cell, the glucose is ‘burned’ – along with oxygen – to produce energy.

When a person has insulin resistance, the pancreas needs to release more insulin than usual to maintain normal blood glucose levels. It is thought that more than a quarter of the population has some degree of resistance to insulin.

The link to diabetes
Insulin resistance increases your risk of developing type 2 diabetes and is found in most people with this type of diabetes. If the pancreas can’t produce extra insulin to overcome your body’s resistance, your blood glucose levels will rise and you will develop impaired glucose tolerance (IGT) or diabetes. People with type 2 diabetes frequently also have other features of metabolic syndrome and a significantly increased risk of cardiovascular (heart and blood vessel) disease.

Central obesity
Central obesity is when the main deposits of body fat are around the abdomen and the upper body. The greater your waist circumference, the higher your risk. A person’s risk for central obesity varies depending on their gender and ethnic background. As a general rule, if your waist measures 94cm or more (men) or 80cm or more (women), you probably need to lose some weight. Men from Middle Eastern, South Asian, Chinese, Asian-Indian, South and Central American ethnic backgrounds are considered at risk if their waist measures 90cm or more.

High blood pressure (hypertension)
In the absence of other risk factors, hypertension occurs when a person has a blood pressure higher than 140/90mmHg. This may be due to genetics, lifestyle or other diseases such as kidney or cardiovascular disease. High blood pressure also increases your risk of developing cardiovascular disease, stroke and kidney disease.

The ideal blood pressure range is less than 130/80mmHg (or lower, if other diseases are present), but everyone is different. Consult with your doctor to find the right target for you and make sure you are monitored regularly.

Lifestyle changes such as regular physical activity, not smoking, reducing the amount of sodium (salt) in the diet, reducing stress, limiting alcohol and achieving a healthy body weight may help but often medication is required.

Cholesterol and triglycerides
Cholesterol is a fatty substance that we make in our liver. LDL (low density lipoproteins) cholesterol can block arteries by building up on the walls of blood vessels. HDL (high density lipoproteins) cholesterol helps protect against this build-up of fatty blockages.

Triglycerides may come from foods we eat but they are also produced by the liver. Drinking excess alcohol can contribute to an increase in triglycerides. If you are insulin resistant, you are likely to have higher-than-normal triglyceride levels. High blood triglycerides tend to be associated with low levels of HDL cholesterol – the ‘good’ or protective cholesterol.

Raised triglycerides and reduced HDL cholesterol increase your risk for atherosclerosis (narrowing of the arteries), which is a contributing factor in heart disease. Overweight or obesity is also a risk factor in itself for conditions such as high triglyceride levels, high blood pressure and atherosclerosis.

Impaired glucose tolerance (pre-diabetes)
Impaired glucose tolerance (IGT) is sometimes referred to as ‘pre-diabetes’. This occurs when your blood glucose level is higher than normal but not high enough to be called diabetes. One-third of people who have impaired glucose tolerance (IGT) or impaired fasting glucose (IFG) will develop diabetes unless lifestyle changes are made.

Does one condition trigger the others?
All of these conditions are interlinked in complicated ways and it is difficult to work out the chain of events. Which condition – if any – is the ‘main trigger’? Some researchers consider that obesity could be the starting point for metabolic syndrome. If you reduce your body weight by 7–10 per cent and participate in 180 minutes of physical activity each week, you may lower your blood pressure and increase your body’s response to insulin. This may help prevent you from developing type 2 diabetes.

Ways to reduce your risk
More than half of all Australians have at least one of the metabolic syndrome conditions. Suggestions for reducing your risk include:

Incorporate as many positive lifestyle changes as you can – eating a healthy diet, exercising regularly and losing weight will dramatically reduce your risk of diseases associated with metabolic syndrome such as diabetes and heart disease.
Make dietary changes – eat plenty of natural wholegrain foods, vegetables and fruit. To help with weight loss, reduce the amount of food you eat and limit foods high in fat or sugar. Reduce saturated fats such as meat, full cream dairy and many processed foods – this will help improve your cholesterol levels. Stop drinking alcohol or reduce your intake to less than two standard drinks a day – this may help to lower triglyceride levels.
Increase your physical activity level – regular exercise raises the level of HDL (‘good’) cholesterol in your blood, which helps remove excess cholesterol from your body and protect against heart disease. Muscle cells that are regularly exercised are more sensitive to insulin.
Manage your weight – increasing physical activity and improving eating habits will help you lose excess body fat. As a result, your blood pressure may drop and your cells will be more sensitive to insulin.
Quit smoking – smoking increases your risk of cardiovascular disease, stroke, cancer and lung disease. Quitting will have many health benefits, especially if you have metabolic syndrome.
Medication may be required – lifestyle changes are extremely important in the management of metabolic syndrome but sometimes medication may be necessary to manage the different conditions. Some people will need to take antihypertensive tablets to control high blood pressure and/or lipid-lowering medications to keep cholesterol within the recommended limits. The most important thing is to reduce your risk of heart attack, diabetes and stroke.

Consult with your doctor to decide what the best management strategy is for you.

Where to get help

Your doctor
An Accredited Practising Dietitian, contact the Dietitians Association of Australia
Baker IDI Heart and Diabetes Institute Tel. (03) 9258 5000
Diabetes Australia – Vic Tel. 1300 136 588
Quit Victoria Tel. 137 848 www.quit.org.au

Things to remember

Metabolic syndrome is a collection of conditions that occur together and increase your risk of diabetes, stroke and heart disease.
Some of the conditions associated with metabolic syndrome include obesity, high blood pressure, high blood triglycerides, low levels of HDL cholesterol and insulin resistance.
Healthy eating and increased physical activity are the keys to avoiding or overcoming problems related to metabolic syndrome.
Consult with your doctor about ways to manage metabolic syndrome.

You might also be interested in:
Circulatory system.
Diabetes.
Diabetes and healthy eating.
Healthy eating tips.
Triglycerides.

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