Is the third component of metabolic syndrome really predictive of outcomes in type 2 diabetic patients?

The use of the category of metabolic syndrome in patients with type 2 diabetes has been questioned by many authors (1,2). In fact, in most studies performed in the general population, the diagnosis of metabolic syndrome is associated with increased risk of diabetes (3–5) and, to a lesser extent, of cardiovascular disease (6); however, data on the impact of metabolic syndrome on cardiovascular morbidity and mortality in type 2 diabetic patients are inconclusive (7–11). Some authors found that, in type 2 diabetes, the presence of one further component of metabolic syndrome beyond diabetes confers a risk profile similar to that of full metabolic syndrome (12). Furthermore, the Adult Treatment Panel (ATP)-III definition of metabolic syndrome considers five parameters (fasting hyperglycemia, high blood pressure, low HDL cholesterol, hypertriglyceridemia, and high waist circumference) equally relevant for diagnosis, although each one of them is associated to a different extent with insulin resistance (13) and cardiovascular disease (14).