Association between functional capacity and heart rate variability in patients with uncomplicated type 2 diabetes.

OBJECTIVE: We sought to investigate functional capacity, heart rate variability (HRV), as well as their relationship in the patients with uncomplicated type 2 diabetes. METHODS: This cross-sectional observational study included 62 controls and 53 uncomplicated diabetic patients. Included subjects underwent laboratory analysis, 24-h ECG Holter monitoring and cardiopulmonary exercise testing. RESULTS: All parameters of time and frequency domain of HRV were decreased in the diabetic patients. Oxygen uptake at ventilatory threshold (18.3 ± 3.9 vs. 14.6 ± 3.6 mL/kg/min, p < .001), peak oxygen uptake (peak VO2) (27.8 ± 4.1 vs. 19.5 ± 4.3, mL/kg/min, p < .001) and oxygen pulse were significantly lower in the diabetic group, whereas ventilation/carbon dioxide ratio and ventilation/carbon dioxide slope (25.4 ± 2.5 vs. 28.6 ± 3.9, p < .001) were significantly higher in this group. Furthermore, heart rate recovery in the first minute was significantly lower in the diabetic group (26 ± 5 vs. 23 ± 5 beats/min, p = .003). In the whole study population HbA1c and SDNN were independently of other clinical and HRV parameters associated with peak VO2, ventilation/carbon dioxide slope and heart rate recovery in the first minute. CONCLUSIONS: Our investigation showed that both functional capacity and HRV were significantly impaired in uncomplicated diabetic patients. HbA1c, an important parameter of glucose regulation, was independently associated with HRV parameters and functional capacity in the whole study population. This reveals a potentially important role of determination of functional capacity and cardiac autonomic function as important markers of preclinical damage in diabetic population.

Cardiorespiratory fitness and right ventricular mechanics in uncomplicated diabetic patients: Is there any relationship?

AIMS: This study investigated the association between cardiorespiratory fitness and right ventricular (RV) strain in uncomplicated diabetic patients. METHODS: This cross-sectional study involved 70 controls and 61 uncomplicated patients with type 2 diabetes, who underwent laboratory analysis, comprehensive echocardiographic study and cardiopulmonary exercise testing. RESULTS: RV endocardial and mid-myocardial longitudinal strains were significantly reduced in diabetic subjects (- 27.5 ± 4.2% vs. - 25.3 ± 4.3%, p = 0.004 for endocardial strain; - 25.6 ± 3.5% vs. - 24.1 ± 3.2%, p = 0.012 for mid-myocardial strain). The same was revealed for endocardial and mid-myocardial of RV free wall. There was no difference in RV epicardial strain. VO2 was significantly lower in the diabetic group (27.8 ± 4.5 ml/kg/min vs. 21.5 ± 4.2 ml/kg/min, p < 0.001), whereas ventilation/carbon dioxide slope was significantly higher in diabetic subjects (25.4 ± 2.9 vs. 28.6 ± 3.3). Heart rate recovery was significantly lower in diabetic patients. HbA1c and global RV endocardial longitudinal strain were independently associated with peak VO2 and oxygen pulse in the whole study population. CONCLUSION: Diabetes impacts RV mechanics, but endocardial and mid-myocardial layers are more affected than epicardial layer. RV endocardial strain and HbA1c were independently associated with cardiorespiratory fitness in the whole study population. Our findings show that impairment in RV strain and cardiorespiratory fitness may be useful indicators in early type 2 diabetes, prior to the development of further complications.