Metabolic syndrome useful to predict risk for diabetes, not CVD

Researchers suggest separate risk algorithms for each disease.

It may not be helpful to use metabolic syndrome criteria to simultaneously predict risk for both diabetes and cardiovascular disease.

Outcome data from two prospective studies suggested that metabolic syndrome and its individual components are associated with subsequent risk for type 2 diabetes, particularly fasting glucose, but there is no association with risk for cardiovascular disease in elderly individuals.

“It is impossible to design criteria to usefully pick up risk for both CVD and diabetes at the same time. The risk factors for the two conditions are simply too different,” Naveed Sattar, MD, PhD, told Endocrine Today.

The focus should be on establishing optimum risk algorithms for each disease, researchers from the United Kingdom and the Netherlands wrote in Lancet.

Two prospective studies

Researchers with the PROSPER study examined the risk for incident CVD and type 2 diabetes in 4,812 individuals aged 70 to 82. Sattar and colleagues used National Cholesterol Education Program criteria for metabolic syndrome.

During three years of PROSPER, 772 individuals developed incident CVD and 287 developed diabetes. No association was identified between metabolic syndrome and increased risk for CVD among individuals without disease at baseline; however, an association between metabolic syndrome and each of its individual components was identified with increased risk for diabetes. The same associations were present in individuals with existing CVD at baseline.

The aforementioned data were then examined in a second prospective study — the British Regional Heart Study — of 2,737 non-diabetic men aged 60 to 79.

During seven years, 440 individuals developed incident CVD and 105 developed diabetes. Unlike in PROSPER, there was a modest association between metabolic syndrome and incident CVD, despite a strong association with diabetes.

Both PROSPER and the British Regional Heart Study had two things in common — all five components of the metabolic syndrome were associated with risk for new-onset diabetes whereas triglycerides, glucose cut-off points and BMI or waist circumference were not associated with risk for CVD.

“Metabolic syndrome criteria are not clinically useful and we should stop using them in clinical practice. We have better and simpler methods to predict risk for heart disease,” such as Framingham Risk Score and fasting glucose, said Sattar, professor of metabolic medicine, BHF Glasgow Cardiovascular Research Center.

Other prediction tests are better

In an accompanying editorial, Richard Kahn, PhD, chief scientific and medical officer of the American Diabetes Association, said these findings “put yet another nail in the coffin of the metabolic syndrome.”

“That people with metabolic syndrome are at increased risk for CVD events or diabetes does not mean that the construct is useful for risk prediction in itself or compared with other approaches,” he wrote.

Like Sattar, Kahn said other tests are better for predicting CVD and diabetes than metabolic syndrome, such as the fasting plasma glucose test.

“What seems to make the most sense is for clinicians to focus on global risk assessment that takes into account all the well-established cardiometabolic risk factors and then to treat each abnormality appropriately,” he wrote. – by Katie Kalvaitis

The findings from the study reported in Lancet confirm a number of previous analyses showing that metabolic syndrome does not add to its individual components in risk for cardiovascular outcome. Furthermore, factors such as cigarette use and LDL not included in metabolic syndrome are well recognized to be important risk mediators that must also be taken into account in cardiovascular disease prevention. Why, then, might it be useful to continue to use the concept of metabolic syndrome if we already have all these readily measured components, which are continuous variables, offering greater sensitivity in discimination of the degree of abnormality? In my opinion, the syndrome allows the health care provider to add the concept of insulin resistance to the ascertainment of high-risk patients, in a fashion compatible with a natural thought process, that of establishment of a categorical variable. By characterizing patients as those with or without metabolic syndrome, we add a conceptual dimension that helps in addressing aspects of the underlying pathogenesis of adverse vascular outcome.

– Zachary T. Bloomgarden, MD

Endocrine Today Editorial Board member

For more information:

• Sattar N, McConnachie A, Shaper AG, et al. Can metabolic syndrome usefully predict cardiovascular disease and diabetes? Outcome data from two prospective studies. Lancet. 2008;doi:10.1016/S0140-6736(08)60602-9.
• Kahn R. Metabolic syndrome — what is the clinical usefulness? Lancet. 2008;doi:10.1016/S0140-6736(08)60731-X.