Dr Matt Doyle gives a round-up of the latest thinking on another key nMRCGP subject
What is it?
The metabolic syndrome emphasises the tendency for risk factors to clump together. Insulin resistance, hypertension, obesity and dyslipidaemia are all featured, as well as pro-thrombotic and pro-inflammatory tendencies.
First suggested as early as 1923 (Kylin) when an association was made between hypertension, hyperglycaemia and gout.
Further refined in 1998 when Reaven suggested 'syndrome X' of insulin resistance and associated risk factors.
Patients with the metabolic syndrome are susceptible to cardiovascular disease and developing diabetes, with a three-fold increased risk of CVD and a five-fold increased risk of type 2 diabetes.
There is still much controversy over its existence as a true syndrome.
Nurture or nature? There is strong evidence for the rise in central obesity in the population affecting incidence of type 2 diabetes but likely genetic involvement too. The metabolic syndrome increases in incidence with age and post-menopausally. Polycystic ovarian syndrome has many features in common.
It is suggested that central obesity may trigger deactivation of nuclear peroxisome proliferators activated receptors leading to insulin resistance. Physical inactivity and carbohydrate rich diets (>60 per cent calorific intake) are also implicated.
Several definitions are currently available. JBS2 (Joint British Societies, 2005) suggest using the National Cholesterol Educational Program guidelines from 2001. Three or more of the following:
• Waist circumference – men >102cm; women >88cm
• BP – =130/85mmHg
• Fasting glucose – =6.1mmol/l
• Serum triglycerides – =1.7mmol/l
• HDL cholesterol – men <1.0mmol ;="" women="">1.0mmol><1.3>1.3>
The above criteria are applicable only to those of European descent. Also in use are the International Diabetes Federation suggestions.
Knowing that we need to treat patients with insulin resistance, dyslipidaemia and so on is hardly new. The identification of this particular group of patients as having metabolic syndrome moves the treatment firmly into primary prevention territory.
Unknown if treatment reduces overall impact of disease.
Initial treatment is alteration of lifestyle; exercise, diet and smoking cessation. There are several studies showing how effective and important this is. Unfortunately com-pliance and persistence can be long-term problems.
Statins are always going to be the
front-runner for managing dyslipidaemia; there is also increasing evidence for fibrates as primary treatment in the metabolic
Hypertension: ACE inhibitors and angiotensin-II receptor antagonists, espec-
ially in those patients without frank
Metformin is still the best drug initially for glucose management. Some trials suggest good results with acarbose and the thiazolidinediones.
Matt Doyle passed the MRCGP last year and works as a full-time partner in St Ives, Cambridgeshire