Impact of diabetes and diastolic dysfunction on exercise capacity in normotensive patients without coronary artery disease

OBJECTIVE: The aim of this study was to determine the impact of diabetes and diastolic dysfunction on exercise capacity in asymptomatic, normotensive patients with type 2 diabetes without coronary artery disease. METHODS: A total of 43 type 2 diabetes patients (age: 50 ± 5 years) and 20 healthy controls (age: 48 ± 4 years) were enrolled. Diastolic function was investigated by conventional pulsed-wave (PW) Doppler and tissue Doppler imaging (TDI). Exercise capacity was evaluated with cardiopulmonary exercise testing (CPET). RESULTS: In patients with type 2 diabetes, increase in resting heart rate (HR-rest) (p = 0.013), decrease in maximum heart rate during exercise (HR-max) (p < 0.001) and exercise time (p < 0.001) compared with controls were significant. Patients had significantly increased minute ventilation volume (VE)/maximum carbon dioxide discharge (VCO2) ratio (p < 0.001), decreased maximum oxygen consumption (VO2-max) (p < 0.001), oxygen consumption at anaerobic threshold (VO2-an) (p < 0.001) and maximum carbon dioxide discharge (VCO2) (p < 0.001) compared to controls indicating significantly reduced exercise capacity. HbA1c was inversely correlated with VO2-max (r = -0.456, p < 0.01) independent of the absence or presence of mild diastolic dysfunction. CONCLUSION: Exercise capacity was found to be significantly decreased in normotensive patients with type 2 diabetes without coronary artery disease, and this decrease was independent of diastolic dysfunction.