['There is increasing evidence for the importance of peripheral abnormalities in the pathogenesis and progression of heart failure (HF). Recently, glucose and insulin metabolism abnormalities have been intensively investigated in patients with HF.', 'To investigate whether coexistence of impaired glucose tolerance (IGT) may decrease exercise tolerance and influence ventilatory response to exercise in patients with systolic HF.', 'Maximal cardiopulmonary exercise test with evaluation of peak VO2 and VE/VCO2 slope and oral glucose tolerance test were performed in 64 clinically stable patients with HF and LVEF <45%.', 'Impaired glucose tolerance was diagnosed in 26 (41%) patients and normal glucose tolerance (NGT) in 38 (59%) patients. There were no significant differences in baseline clinical characteristics or LVEF between groups. There were significant differences in peak VO2 between IGT and NGT (15.4+/-4.1 vs. 18.7+/-4.2 ml/kg/min respectively; p=0.003) and VE/VCO2 slope (35.7+/-7.3 vs. 31.8+/-5.7 respectively; p=0.02). The IGT was independently related to peak VO2 and VE/VCO2 slope in multivariate regression analysis.'] Does impaired glucose tolerance worsen exercise capacity and ventilatory response to exercise in patients with chronic heart failure?