Defining the Role of Insulin Resistance in 'Idiopathic' Dilated Cardiomyopathy

Inclusion Criteria: * Diagnosis of nonischemic dilated cardiomyopathy, current NYHA class I-II congestive heart failure * History of Stage C-D heart failure with EF ≤ 40% during the course of the disease * Treatment with a stable comprehensive heart failure regimen for at least 3 months (including beta-blockers and ACE-inhibitors or angiotensin receptor blockers unless intolerant) * Age \> 18 yrs Exclusion Criteria: * Cardiomyopathy due to one of the following: * Ischemic heart disease * Primary valvular lesion * Hypertrophic cardiomyopathy * Cardiac resynchronization within the last 3 months * Transaminase values \> 2.5 x upper limit of normal or history of liver disease * Diagnosis of diabetes mellitus by: * Diabetes previously diagnosed per patient history * 2 or more fasting glucose values \> 125 mg/dl * Current NYHA class III or IV heart failure * Serum creatinine \> 1.6 mg/dl * History of heart transplantation * Pregnancy or active breast feeding * Hospitalization for decompensated heart failure within 30 days prior to enrollment.