The Metabolic Syndrome is best defined as a clustering of closely related medical conditions which increase the risk of developing heart disease and diabetes.

The following features comprise metabolic syndrome that increases risk of future adult diabetes and future heart disease:

increased blood triglyceride (a form of fat) levels
decreased ‘good’ cholesterol levels (HDL cholesterol)
overweight particularly around the abdomen
increased blood pressure
increased blood glucose level

If a person has been diagnosed with three of the above features they have metabolic syndrome.

What causes Metabolic Syndrome?
Several factors may cause an individual to develop the metabolic syndrome, these features are discussed within the sections below. Clinicians and health care professionals know that obesity has a strong link with the development of the metabolic syndrome.

Why is Metabolic Syndrome potentially harmful to your health?
Metabolic syndrome increases the risk of diabetes 5 fold and heart disease by approximately 3 fold.

The metabolic syndrome is present in approximately 20% of adult populations in developed countries and in approximately 80% of people with type 2 diabetes.

The level of obesity is increasing in populations across the world. The occurrence of metabolic syndrome is likely to increase with the rising levels of obesity and will contribute to the epidemic of diabetes. Metabolic syndrome is likely to have a marked impact on the prevalence of heart disease and type 2 diabetes worldwide in the next two decades. Other medical conditions such as fatty liver disease, polycystic ovary syndrome, gallstones, sleep apnoea and certain cancers will also increase worldwide with the increased level of obesity. The biggest impact the metabolic syndrome has on health is the increased risk to heart disease and diabetes.

Obesity has been on the increase over the last few decades during which time most people have been exposed to an energy dense food supply and decreasing levels of physical activity. The metabolic syndrome is strongly associated with obesity particularly if fat is stored around the abdomen. High triglyceride levels have been found to be a contributing factor of the metabolic syndrome (calories that are consumed and not burnt are converted into triglycerides and transported by the blood to fat cells for storage).

The influence of obesity on the incidence of the metabolic syndrome has also been observed in children over recent years and obesity is now an important cause of type 2 diabetes occurring in children.

Some ethnic groups have a higher predisposition to central obesity than others, for example, the amount of central obesity is greater among South Asians than Europeans and is greater among Europeans than African-Caribbeans.

Low birth weight may also increase the risk of the metabolic syndrome when it is linked with obesity in adulthood and we and others are undertaking research in this area. 

Each feature of the metabolic syndrome is determined by complex gene-environment interactions. Certain components of the metabolic syndrome may be more strongly influenced by the environment, others by genetic inheritance, and some by early development. Metabolic syndrome also increases with age.

Other hormones besides insulin can influence the metabolic syndrome. Specifically hyperandrogenemia (excessive secretion of androgen [male sex hormone]) can occur with polycystic ovary syndrome that has many of the features of the metabolic syndrome. The menopause may also influence development of the metabolic syndrome since body composition alters unfavourably after the menopause, in part, because of the low levels of the female sex hormone oestrogen that occur with the menopause.

What is the link between too much body fat and metabolic syndrome?

Central fat accumulation (fat stored around the abdomen) is strongly associated with insulin resistance. Impaired action of insulin is an important feature of the metabolic syndrome.

Insulin is a hormone produced by the body during the digestion process which allows glucose to be absorbed from the blood into the body. The term insulin resistance means that insulin does not work properly and a high level of glucose remains in the bloodstream because insulin is not able to control blood glucose as effectively. Health care professionals consider that insulin resistance is a significant contributor to the development of type 2 diabetes.

In relation to the metabolic syndrome insulin resistance is linked predominantly to a cluster of disorders involving triglyceride (a form of fat) and glucose metabolism, increased blood pressure and vascular inflammation. Although to date there is no central unifying mechanism that explains all of the features of the syndrome, it is most likely that certain of the features occur as secondary consequences of a primary (or several primary) abnormalities. Given that insulin resistance is fundamental to the syndrome an understanding of the cause and consequences of insulin resistance and its consequences is crucial to an understanding of the causes of the metabolic syndrome.

Clinicians and health care professionals use the following two methods to calculate if a person is overweight or obese to identify whether they may have body fat that is linked to the metabolic syndrome:

• by measuring their waist circumference
• by measuring their body mass index (BMI)

Waist circumference measurement thresholds:

Men: Greater than 102 cms
Women: Greater than 88 cms

At the end of 2005 these thresholds were considered a little too ‘generous’ and, therefore, for people of white Northern European extraction revised thresholds were recommended: men > 94 cms, women > 80 cms. In addition waist circumference thresholds have been established for people from other ethnic groups e.g. South Asians and Chinese: men > 90 cms; women > 80 cms.

Body mass index (BMI - Kg/m2):

Less than 18.5 = Underweight

18.5 – 24.9 = Normal

25.0 – 29.9 = Overweight

30 and Above = Obese

The formula for calculating BMI is: BMI=Kg/m2

            How to calculate your BMI:

Weight in kg
 _____________

Height in metres x height in metres

            Kg/m2

            = e.g. 70 kg
         _____________

        1.92m x 1.92 m

        = 70
        ______

        3.69
 

        BMI = 19 kg/m2 = normal body fat.

                                                *******************************

To establish whether you have metabolic syndrome we suggest using the National Cholesterol Education Program Adult Treatment Panel (ATP III) guidelines. The presence of 3 out of 5 of the following measurements is necessary to identify the syndrome:

1. Waist measurement Men: Greater than 102 cms Women: Greater than 88 cms

2. Blood pressure greater than or equal to 130/85

3. Triglyceride levels greater than or equal to 1.7 mmol/l

4. Glucose level: greater than or equal to 6 mmol/l

5. HDL cholesterol

Men: less than or equal to 1.0 mmol
Women: less than or equal to 1.3 mmol/l

Why is waist circumference used as a measure of overweight rather than BMI?
BMI does not take into account that somebody may be heavy just because they have a large muscle bulk - are of a muscular build, (for example, body builders), and not because they have fat accumulation. Moreover, we know that it is the central fat around the abdomen (apple shape of fat distribution) not just total body fat collection i.e. hips (pear shape of fat distribution) that leads to insulin resistance, fatty liver and other problems seen in metabolic syndrome. Therefore, BMI is not an ideal ‘marker’ of central fat, which is a key player in the cause and diagnosis of metabolic syndrome.

What can an individual do to help themselves if they have metabolic syndrome?

Treatments for the Metabolic Syndrome:

Weight loss should be a priority for people with metabolic syndrome, and will result in improvement of most of the features of the syndrome. Weight loss can be achieved with modification of diet and increased physical activity.

Dietary recommendations for people with the metabolic syndrome should include reduction in calorie intake for people who need to lose weight and general advice about a healthy diet (eat plenty of fruit and vegetables maybe as much as ten portions each day and reduce salt and sugar intake). Be careful with heavily processed foods – they are often rich in salt, sugar and fat. Processed foods often contain high levels of hydrogenated fats (unsaturated fats that are altered in the cooking process). There is increasing evidence that these types of fats may be bad for our blood vessels and be linked to heart disease and stroke. Be careful with all carbohydrates in the diet, it is very difficult to gauge the correct portion size with foods such as bread, potatoes, rice, pasta, pizza, cereals, pulses, couscous. If the portion size is too great the calorie intake will be too great and this will predispose to gaining body fat.

Increasing physical activity can contribute to weight loss and also has beneficial effects on cardiovascular risk factors and insulin action. Half an hour of moderate-intensity exercise each day is recommended for general populations but, for people who wish to lose weight and are physically able, an hour of brisk walking in addition to other activities is recommended. Often buying a simple pedometer is a good adjunct to monitoring physical activity. For all adults it is recommended that a minimum of 10,000 steps per day should be the goal unless this level of physical activity is considered potentially detrimental (to you) by your doctor, for example, because of angina.

Although there are data on excess morbidity and mortality associated with the metabolic syndrome, at present there are no published studies treating the metabolic syndrome to examine whether treatments reduce development of type 2 diabetes and heart disease. However, there is plenty of evidence for treating the individual components of the syndrome. Because insulin resistance and central obesity are the central components of the syndrome, lifestyle interventions lie at the heart of treatment. Exercise training has been shown to improve features of the metabolic syndrome.

For subjects with abnormal glucose metabolism, there are several studies showing that lifestyle modification can decrease the rate of progression to diabetes. In the Finnish Diabetes Prevention Trial, lifestyle changes including weight loss of 4 kg over 3 years, 150 min of exercise per week, a low fat, high fibre diet and smoking cessation decreased the risk of diabetes by 58% compared to the control group. The American Diabetes Prevention Program compared similar lifestyle modifications with a mean weight loss of 7% in the intervention group and found a similar reduction in the development of diabetes. In the Da Quing Diabetes prevention study, diet alone reduced diabetes by 31%, exercise alone reduced diabetes by 46% and the combination of both reduced diabetes by 42% suggesting that exercise is a major component of benefit in protecting against diabetes.

Studies of drug intervention to prevent diabetes show less impressive reductions in diabetes incidence with the ‘anti fat’ treatment orlistat reducing diabetes by 37%, other treatments to decrease glucose used in adult diabetes such as acabose reduced diabetes by 36%, metformin by 22%.

The most effective cholesterol lowering drugs to decrease risk of heart disease and strokes are the ‘statins’ and treatment with these drugs is advised if risk of a cardiovascular event such as a stroke or a heart attack is considered to be high by the doctor (> 20% risk over 10 years).

The most effective drugs to treat the dyslipidaemia of the metabolic syndrome are the fibrates (FENOFIBRATE) and nicotinic acid derivatives (NIASPAN)*.

Lifestyle modifications, including decreasing salt intake, are recommended for the hypertension of the metabolic syndrome although antihypertensive drugs are usually required to control blood pressure. Angiotensin converting enzyme inhibitors and angiotensin II receptor blocking drugs are often the drugs of choice as in addition to their blood pressure lowering effect they can improve insulin sensitivity and decrease the rate of progression to diabetes by 14-34% compared with older drugs or placebo.

*These drugs can be combined with statins to decrease risk of heart attack and stroke if necessary.