Research from the University of Glasgow reported in today's issue of Journal of the American Heart Association finds that men who have at least three metabolic abnormalities are at high risk of developing type 2 diabetes and heart disease,

Using a new, simplified definition of the "metabolic syndrome"ﾖ the clustering of certain metabolic-related heart risk factors ﾖ researchers were able to predict diabetes and coronary heart disease (CHD) at an early stage in development.

"This is important because early prediction might allow lifestyle changes to delay or derail the disease process", says lead author Dr Naveed Sattar, an honorary consultant in clinical biochemistry at the University of Glasgow Royal Infirmary .

The new definition of metabolic syndrome, also known as syndrome X, developed by the U.S. National Cholesterol Education Panel (NCEP) incorporates thresholds for five easily measured variables: abdominal obesity, elevated triglycerides, low levels of HDL or "good" cholesterol, high fasting blood sugar (glucose) and high blood pressure. Having any three of the five conditions would be considered the metabolic syndrome.

A previous definition by the World Health Organization required that individuals with normal glucose tolerance have documented evidence of insulin resistance ﾖ the body's inability use insulin efficiently. However, insulin resistance often appears before glucose intolerance ﾖ the body's inability to metabolize blood sugar, which leads to type 2 diabetes.

"This is a weakness because problems with glucose metabolism usually develop rather late in the syndrome. Glucose intolerance is usually the fourth or fifth condition to appear," Sattar says.

Although researchers already know that metabolic syndrome predisposes people to CHD and diabetes, there was little data on whether the new simpler definition would be as predictive as the more stringent older criteria.

"This is the first study to show that the new criteria predict excess risk for both CHD and diabetes," he says.

Researchers used data collected from 6,447 men in the West of Scotland Coronary Prevention Study (WOSCOPS) to test the definition recently proposed by NCEP. WOSCOPS is a primary prevention trial that proved the effectiveness of the cholesterol-lowering drug pravastatin for reducing heart disease death and disability. For that reason, all of the men had moderately elevated cholesterol levels. Sattar's group substituted body mass index figures collected in WOSCOPS for abdominal obesity.

Using the new definition, 26 percent of the men in the study had metabolic syndrome. Those with the metabolic syndrome had 1.7 times the risk of a CHD event and 3.5 times the risk of developing diabetes during 4.9 years of follow up.

The risk increased as the number of metabolic abnormalities rose. Men with four or five features of metabolic syndrome had 3.7 times the risk of coronary heart disease and 24.5 times the risk of diabetes compared to those with no abnormalities.

"The diabetes finding is particularly striking because currently there are few predictive screening charts to identify people at high risk of becoming diabetic as there are for CHD ", Sattar added.

Interestingly, the cholesterol lowering drug seemed equally beneficial for men with and without the metabolic syndrome, reducing the risk of CHD 27 percent in those with metabolic syndrome and 31 percent in those without the syndrome, he says.

Sattar's group also looked at another variable, the inflammatory marker C-reactive protein (CRP) that other studies have linked to the development of heart disease and diabetes. They found that CRP levels were higher in the 26 percent of the subjects with metabolic syndrome than in those without the syndrome.

"This research adds to the potential importance of using metabolic syndrome criteria to identify individuals at risk for CHD and diabetes who may benefit from aggressive lifestyle changes. Those changes include losing weight and getting more exercise, which can slow the progression of coronary heart disease and even some people avoid diabetes," Sattar concludes.

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Co-authors are Allan Gaw, M.D.; Olga Scherbakova; Ian Ford, Ph.D.; Denis St. J. O?Reilly, M.D.; Steven M. Haffner, M.D.; Chris Isles, M.D.; Peter W. Macfarlane, D.Sc.; Chris J. Packard, D.Sc.; Stuart M. Cobbe, M.D.; and James Shepherd, M.D.End

First published: 15 July 2003