Insulin resistance in idiopathic dilated cardiomyopathy - A possible etiologic link

OBJECTIVES This study was designed to quantify the prevalence of abnormal glucose tolerance and insulin resistance in patients with idiopathic dilated cardiomyopathy (IDCM). BACKGROUND Insulin resistance is an independent risk factor for mortality in patients with heart failure (HF) and is a known risk factor for ischemic cardiomyopathy. Though potential physiologic links between insulin resistance and HF have been hypothesized, the relationship between insulin resistance and IDCM remains unclear. METHODS A total of 230 consecutive patients from a university HF clinic were screened for IDCM, the absence of diabetes mellitus, and the lack of significant co-morbid conditions. Oral glucose tolerance tests were performed in the 43 patients with IDCM who met these criteria, and their plasma glucose and insulin responses were compared with those of 40 healthy volunteers, matched for age, gender, and body mass index. RESULTS Plasma glucose responses were higher during the oral glucose tolerance tests in patients with IDCM (p < 0.01), associated with significantly higher plasma insulin concentrations following the oral glucose challenge (p < 0.01). In addition, abnormalities of glucose tolerance were significantly (p < 0.05) more common in patients with IDCM (49% vs. 23%). CONCLUSIONS Insulin resistance and abnormal glucose tolerance are more prevalent in patients with IDCM and represent potentially reversible metabolic derangements in these individuals. (C) 2004 by the American College of Cardiology Foundation.