Jean-Pierre Després
Québec Heart Institute
Laval University, Canada

First of all, we need to identify the most prevalent cause of the Metabolic Syndrome in our population: we are exposed to a sedentary affluent environment where daily energy expenditure related to work and activities has decreased, while our population is exposed to a diet which is dense in calories due to its high content of fat and/or refined sugar. This "toxic" environment generates a positive energy balance and weight gain, which explains the increasing prevalence of obesity that has reached epidemic proportions world-wide. As type 2 diabetes is most often accompanied by obesity, there is therefore a parallel increase in the prevalence of both obesity and of type 2 diabetes all over the world.

With this evolving landscape of a growing number of obese and/or type 2 diabetic patients, the Metabolic Syndrome has become a major issue because of its impact on cardiovascular disease risk. Indeed, there is increasing evidence suggesting that although it is by all means appropriate to aim at a better management of the hyperglycaemic state of type 2 diabetic patients, hyperglycaemia does not appear to be the main culprit responsible for the markedly increased cardiovascular disease risk in this population. Rather, studies have suggested that a cluster of metabolic abnormalities which includes an atherogenic dyslipidaemic state, an impaired glucose/insulin homeostasis, a prothrombotic/inflammatory profile as well as an endothelial dysfunction, substantially increases the risk of coronary heart disease in type 2 diabetic patients independently from the level of glycaemic control. Thus, these results imply that in order to reduce the risk of atherosclerotic macrovascular disease, physicians need not only to focus on a better glycaemic control in type 2 diabetic patients but also to improve the features of the Metabolic Syndrome.

These findings have the following implications: if hyperglycaemia does not largely mediate the increased risk of coronary heart disease in type 2 diabetic patients, even a non-diabetic patient with the features of the Metabolic Syndrome should also be at increased risk of coronary heart disease. This is exactly the conclusion that we reached in the Québec Cardiovascular Study, a prospective observational study of a sample of asymptomatic middle-aged men that we followed for incidence of a first ischaemic heart disease event over 5 years. We found that even in the absence of diabetes, non-diabetic men with the features of the Metabolic Syndrome such as the high triglyceride-low HDL-cholesterol, elevated apo B, small dense LDL-dyslipidaemia and an increased C-reactive protein concentration were at markedly increased risk of ischaemic heart disease.

Therefore, the epidemic proportion reached by the Metabolic Syndrome in our population represents a major public health challenge. For instance, patients with a Metabolic Syndrome are highly prevalent in our tertiary cardiology centres, in diabetes units, in hypertension clinics as well as in lipid clinics. There is, therefore, a need for proper integration of disciplines in order to adequately evaluate the risk in patients with the Metabolic Syndrome as well as to develop integrated approaches for a better management of their clustering metabolic abnormalities.

Finally, as patients with the Metabolic Syndrome do not necessarily have increased LDL-cholesterol levels, their markedly elevated coronary heart disease risk provides evidence that we need to go beyond LDL-cholesterol measurement and lowering for the proper management of this high-risk population of patients.