Influence of Complications of Diabetes Mellitus on Exercise Tolerance of Patients with Heart Failure: Focusing on autonomic nervous activity and heart rate response during cardiopulmonary exercise tests

Abstract

Purpose: The purpose of this study was to clarify the influence of complications of diabetes on the exercise tolerance of patients with heart failure. Methods: The subjects of this study were 69 patients (44 men; mean age: 62.2 ± 13.4 years) who were hospitalized and diagnosed with heart failure between November 2016 and November 2017. The subjects all took part in a cardiopulmonary exercise test. The patients' medical background, indexes obtained from lower-limb muscle strength and the cardiopulmonary exercise test, heart rate response indexes [Δ heart rate (ΔHR)], and autonomic nervous activities were measured, and these individual indexes were compared between the diabetic group and the non-diabetic group. Results: Compared with the non-diabetic group, the peak oxygen uptake (peak VO₂) and ΔHR in the diabetic group were significantly lower (13.0 ± 2.2 vs. 14.9 ± 4.4 ml/kg/min and 27.2 ± 11.7 vs. 36.7 ± 14.7 bpm, respectively) (p<0.05). Regarding the autonomic nervous activity during the cardiopulmonary exercise test in the diabetic group, there was a significant decrease of parasympathetic nerve activity and a significant lack of increase in sympathetic nerve activity (p<0.05). Conclusions: Patients with heart failure and diabetes had lower levels of exercise tolerance, as compared with patients without complications. It was suggested that the decrease in heart rate response was due to the decrease of autonomic nervous activity and that this may play a role in reduced exercise tolerance.