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University of Glasgow researchers have found that metabolic syndrome — a combination of medical disorders thought to increase risk of both diabetes and cardiovascular disease — in fact only increases the risk of diabetes in the elderly.

The findings of the team, led by Naveed Sattar, professor of metabolic medicine, are published in the forthcoming edition of The Lancet.

The metabolic syndrome criteria require individuals to have three of the five following abnormalities: raised blood sugar levels, high blood pressure, high waist circumference, decreased levels of the healthy cholesterol (called HDL cholesterol), and elevated levels of triglycerides (fats) in the blood.

Criteria for metabolic syndrome were developed to improve understanding of links between the pre-diabetes state and heart disease, and were touted to be simpler way to simultaneously identify individuals at risk of either condition.

However, their clinical role remains very contentious since the criteria do not include other well established risk factors for heart disease such as age, cholesterol and smoking.

Professor Naveed Sattar, from the BHF Glasgow Cardiovascular Research Centre at the University of Glasgow investigated to what extent metabolic syndrome and its individual components were related to risk of these two diseases in elderly populations.

They analysed data from 4812 non-diabetic people aged 70-82 years from the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER), and corroborated this data in a second prospective study (the British Regional Heart Study [BRHS]) of 2737 non-diabetic men aged 60-79 years.

In PROPSER, 772 cases of CVD and 287 of diabetes occurred in just over three years. Metabolic syndrome was not associated with increased risk of CVD in those without baseline disease, but was associated with a more-than-four-fold increased risk of diabetes.

Results were similar in participants with existing CVD. In BRHS, 440 cases of CVD and 105 of diabetes occurred over seven years. Metabolic syndrome was associated with a modest (27%) increased risk of CVD, but a more than seven-fold increased risk of diabetes. In both studies, body mass index or waist circumference, triglyceride levels, and glucose cutoff points were not associated with risk of cardiovascular disease, but all five components were associated with risk of new-onset diabetes.

The authors conclude: “Metabolic syndrome and its components are associated with type 2 diabetes but have weak or no association with vascular risk in elderly populations, suggesting that attempts to define criteria that simultaneously predict risk for both cardiovascular disease and diabetes are unhelpful”.  The authors conclude that rather than having a combined criteria, clinical focus should remain on establishing optimum and separate risk criteria for each disease.

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For more information, contact Ray McHugh in the University of Glasgow Media Relations Office on 0141 330 3535 or email r.mchugh@admin.gla.ac.uk

First published: 21 May 2008