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A new definition for the metabolic syndrome |
 The metabolic syndrome sometimes called syndrome X or the insulin resistance syndrome has had a number of definitions over the last few years but we seem to have now settled on a much more simplified and practical definition from the International Diabetes Federation released in April 2005 at the 1st International Congress on Prediabetes and the Metabolic Syndrome held in Berlin. If this definition is applied to Australia we have about one third of our population affected which makes it a very significant health burden.
Of note with the new definition is the reduced waist circumference cf the US definition - waist circumference of >/= 94 cm for Europoid men and >/= 80 cm for Europoid women. The US is for now sticking to 102 cm for men and 88cm for women. Note that some ethnic groups have slightly lower readings - (for these and the full definition see boxed chart).
Also note that this cluster of risk factors for heart disease and strokes focuses on a particular atherogenic dyslipidaemia of high triglycerides and low HDL and is often found with insulin resistance with or without type 2 diabetes.
The relevance of the metabolic syndrome
Having the metabolic syndrome triples the risk of having a coronary or stroke and twice as likely to die from these events as well as five times more likely to develop type 2 diabetes if not already present. When GPs diagnose a patient with abnormal girth, blood pressure, lipid levels and fasting sugar levels there is already an atherogenic process evolving associated with insulin resistance. These macro-vascular complications begin many years before the sugar levels become abnormal unlike the nephropathy, retinopathy and neuropathic microvascular complications which come on after type 2 diabetes develops, particularly when control of blood sugars falls below target levels.
The relevance of this is that early diagnosis and intervention is needed to prevent the atherogenic complications in later life. LDL cholesterol is not in the syndrome cluster but that does not mean it is unimportant and raised levels add to risk and should be kept at target levels with diet and medication. When type 2 diabetes has developed LDL targets should be as strict as if there has already been a cardiac ischaemic event.
Treating the metabolic syndrome
After identifying the metabolic syndrome the management needs to be directed at minimising the complications and reducing the risk of cardiovascular disease including addressing smoking status. Then there is primary prevention which is basically lifestyle management. Sometimes people who don’t respond to this therapeutic lifestyle change or need to go further with weight management and risk factor reduction may need medication.
Also high blood pressure may need to be addressed. Whilst weight loss does reduce blood pressure that may not be enough for some people and medications may need to be used. If blood sugar levels are in the type 2 diabetic range hypoglycaemic agents like metformin will be needed. There are not yet clear guidelines as to whether metformin should be used in the pre-diabetic state but there is some evidence that it may help prevent or delay the onset of type 2 diabetes but is not as effective as intensive lifestyle intervention.(1), (2).
Therapeutic lifestyle change
Lifestyle change is a challenge for anyone in particular for those who have entrenched habits that may be pleasurable, eg eating lots of high energy dense food and being sedentary. There is no way this behaviour can be reversed unless the person is ready for change.
Assessment of readiness for change is the first matter to be addressed and advice tailored to that mental state. If somebody is in a pre-contemplative state relating to lifestyle change then all the GP can do is show concern and point out the risk of continuing with such a lifestyle. On the other hand if somebody is ready for change then the therapist can educate and coach their patient in strategies to improve their health.
The main thrust of advice should be directed at:
(1) Making more healthy choices in food - low fat using monounsaturated fat rather than saturated fat, for carbohydrates move towards low gylcaemic index choices where possible, moderate portion size, include food for hunger management (namely protein and low GI carbohydrates), drink plenty of water, moderate alcohol intake if outside WHO recommended ranges.
(2) Increasing physical activity levels both incidental and planned - both aerobic and resistance activities using the large muscles of both the upper and lower body
(3) Making behavioural changes such as eating slowly preferably at a meal table without a TV on, avoid non-hungry eating, don’t allow oneself to become starving hungry and don’t eat until stuffed full.
Avoiding fad diets like the Atkins and detox should be recommended. They are not nutritionally healthy used long term, nor is there proven sustained weight loss benefit for 2 years or more. The reality is that people won’t stick to these diets long term and when they resume their pre dieting eating patterns they will regain the weight plus more sometimes and very quickly.
The barriers to change - mechanical and motivational
All the above changes are easier said than done and people need a lot of coaching to bring about lifestyle change. As regards increasing levels of physical activity the barriers are largely mechanical. So often people who have the metabolic syndrome also have other conditions such as arthritis in the knees or hips but there are many other mechanical conditions that may also limit physical activity levels. This is where an exercise physiologist or trained gym instructor can be helpful.
The ultimate aim is to help people become masters of their own destiny when it comes to managing their own health. GPs need to become lifestyle physicians. A wide range of health professionals could be trained as lifestyle medicine counsellors for managing the metabolic syndrome. GPs can refer to some of these with the incentive of EPC Medicare benefits. Obesity with related chronic complications present for more than six months may make patients eligible for these benefits.
Dr Andrew Binns is a GP in Goonellabah, NSW, with a particular interest in obesity issues.
(1) Lindstrom J, et al. The Finnish Diabetes Prevention Study: Lifestyle intervention and 3 year results on diet and physical activity. Diabetes Care 2003; 26: 3230-6
(2) Tuomilehto J, et al Prevention of type 2 diabetes mellitus by changes in lifestyle among subjects with impaired glucose tolerance. NEJM 2001; 344:1343-50
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