An abdominal distribution of fat is associated with the greatest heart disease risk, because commonly, several risk factors of metabolic origin cluster in these individuals. When this occurs the condition is called the 'metabolic syndrome'.

Increased activity of the sympathetic nervous system resulting in enhanced release of the stress hormone 'noradrenaline', may be one mechanism by which adverse cardiovascular and metabolic sequela of the metabolic syndrome might be mediated. Impaired insulin action may be one factor contributing to increased noradrenaline release.

The aim of this Study is to determine whether treatment with a drug called pioglitazone which is known to improve insulin action, results in reduced sympathetic nervous system activity and stress hormone release when compared to treatment with a dummy drug (placebo).

The rapidly growing burden of obesity together with a population that is becoming older raises the importance of effective strategies for the primary prevention and treatment of the metabolic syndrome in order to combat the epidemic of type 2 diabetes and to reduce the increased risk of cardiovascular mortality.

Increased sympathetic nervous system activity may participate in the pathogenesis and complications of the metabolic syndrome. This Study will use a randomised controlled design to evaluate the effects of pioglitazone treatment on sympathetic activity in middle-aged subjects with the metabolic syndrome.The results will generate new information on the neuroadrenergic effects of thiazolidinediones in this clinical setting. This is relevant to the understanding of the pathophysiology of the metabolic syndrome and to its clinical management.

• Esler M, Straznicky N, Eikelis N, Masuo K, Lambert G, Lambert E. Mechanisms of sympathetic activation in obesity-related hypertension. Hypertension. 2006 Nov;48(5):787-96. Epub 2006 Sep 25. No abstract available.
• Straznicky NE, Lambert EA, Lambert GW, Masuo K, Esler MD, Nestel PJ. Effects of dietary weight loss on sympathetic activity and cardiac risk factors associated with the metabolic syndrome. J Clin Endocrinol Metab. 2005 Nov;90(11):5998-6005. Epub 2005 Aug 9.

Inclusion Criteria:

• Males and females aged 45-65 years,
• non-smokers,
• HOMA index > 2.5 and
• who meet ATP III criteria for the metabolic syndrome

Exclusion Criteria:

• History of diabetes,
• previous MI, stroke, heart failure, impaired hepatic or renal function.
• Inability to cease medications which may affect study parameters.