Response to Letter by Bosevski
Dr Bosevski wonders if there is a need to estimate indices of insulin resistance in patients with manifest metabolic syndrome to gain further information on the risk for carotid atherosclerosis.
As we presented and discussed in our article,1 estimations of insulin resistance are significantly associated with carotid IMT, when the analysis is unadjusted for the parameters of the metabolic syndrome. In case of adjustment for the components of the metabolic syndrome, just the HOMA-index remained significantly predictive for average carotid IMT. But at least after adjustment for the presence of the metabolic syndrome, this association disappeared. With regard to previous studies in this field, we have to state that in studies that showed a significant association between insulin resistance and cardiovascular events often the adjustment for the metabolic syndrome was insufficient.2,3
Gami and colleagues4 recently published a meta-analysis suggesting that the risk associated with the metabolic syndrome as an entity for cardiovascular events is greater than the sum of the risk components conferred by the individual factors of the syndrome. In our population we could confirm this observation because no insulin resistance measurement remained independently predictive after the adjustment for the presence of the metabolic syndrome according to NCEP-ATPIII criteria. So, we agree with Dr Bosevski that at least in our population neither HOMA nor the insulin resistance estimated by the Short Insulin Tolerance test have any advantage in comparison with the use of easy available parameters of the metabolic syndrome and the diagnosis of a manifest metabolic syndrome. Furthermore, with respect to therapeutic options, no intervention study has yet been done, focusing on insulin resistance as a therapeutic target. We just have evidence for treating every single risk factor within the metabolic syndrome.
Sourij H, Schmoelzer I, Dittrich P, Paulweber B, Iglseder B, Wascher TC. Insulin resistance as a risk factor for carotid atherosclerosis: a comparison of the Homeostasis Model Assessment and the short insulin tolerance test. Stroke. 2008; 39: 1349–1351.
Pyorala M, Miettinen H, Laakso M, Pyorala K. Hyperinsulinemia predicts coronary heart disease risk in healthy middle-aged men: the 22-year follow-up results of the Helsinki Policemen Study. Circulation. 1998; 98: 398–404.