Yuji Matsuzawa
Director of the Sumitomo Hospital, Osaka, Japan

The Metabolic Syndrome can be defined as a condition in which multiple risk factors, such as diabetes mellitus, hyperlipidaemia, hypertension, and upper body obesity cluster and as a highly pro-atherogenic state. However, there is no consensus as to whether this syndrome is a clinical entity or merely the state in which very common risks are clustered only coincidentally in one individual.

I believe Metabolic Syndrome is highly important because I think there is a key factor that induces a variety of risk factors simultaneously in one individual. In addition, I think the key factor may directly relate to vascular changes. In other words, Metabolic Syndrome may be so pro-atherogenic not just because of the clustering of these risk factors, but due to the presence of the key factor itself. By managing this key factor, not only could multiple risk factors be managed all at once without the need for treatment of each condition (diabetes mellitus, hyperlipidaemia, hypertension), but we could also directly prevent the development of atherosclerosis. Insulin resistance used to be considered a key factor for Metabolic Syndrome. Although insulin resistance is one of the factors especially for the occurrence of impaired glucose metabolism, it does not correlate as clearly to hyperlipidaemia or hypertension. In addition, primary or genetic insulin resistance is very rare and most insulin-resistant states are induced by obesity, especially visceral obesity.

Thus, I think that visceral obesity or visceral fat accumulation is the key factor that is located at the upper stream of insulin resistance. There is growing evidence on the mechanism by which visceral adiposity induces diabetes mellitus, hyperlipidaemia, and vascular diseases. The contribution of adipocytokines, including adiponectin, which are released from adipose tissue, to the occurrence of Metabolic Syndrome-related diseases including atherosclerotic diseases has recently been clarified. I believe that management of visceral adiposity or adipocytokine regulation may become very useful in the treatment of Metabolic Syndrome in the near future.