Impaired glucose tolerance--is it relevant for cardiovascular disease?

Although IGT is clearly associated with increased cardiovascular risk factors, there is currently conflicting data regarding the association of IGT with cardiovascular disease. This is true particularly for stronger study designs, namely prospective studies. This is partly because of the relatively few studies instituted since the WHO IGT criteria were developed [1] but also because there may be uncertainty about whether other risk factors such as blood pressure or dyslipidaemia should be controlled for. If one believes that IGT (that is mildly elevated glucose levels) is responsible for increased cardiovascular risk factors, then multivariate adjustment should not be done. Furthermore, the high variability of the oral glucose tolerance test needs to be taken into account. Lastly, if IGT is a risk factor for CHD, it is not clear that the increased risk of CHD is restricted solely to those IGT subjects who convert to NIDDM.