Diabetes verslechtert cardiorespiratoire fitheid en autonome functie bij nierpatiënten

BACKGROUND: Patients with chronic kidney disease (CKD) have reduced cardiorespiratory fitness, which is associated with a higher incidence of cardiovascular disease and mortality. The aim of this study was to investigate the relationship between cardiorespiratory fitness and autonomic nervous system function in patients with chronic kidney disease, with and without diabetes mellitus. METHODS: Seventy-two patients with stage 3-4 chronic kidney disease (27 without diabetes mellitus and 45 with diabetes mellitus), and 22 age-matched controls were included. Autonomic function was assessed through measurement of time, frequency and non-linear components of heart rate variability (HRV) during a 5-min supine electrocardiography recording. Cardiorespiratory fitness (measured by peak oxygen uptake [VO<inf>2peak</inf>]) was assessed by a cardiopulmonary exercise test. RESULTS: Several HRV parameters (6 out of 11 variables) were significantly lower (P<0.05) in patients with chronic kidney disease compared to healthy controls. Further, the majority of HRV parameters, and VO<inf>2peak</inf>, were significantly lower (P<0.05) in the patients with diabetes compared to those without diabetes. A multiple linear regression identified age, body mass index (BMI) and diabetes status as significant predictors of VO<inf>2peak</inf> in patients with CKD (adjusted R2=0.51, P<0.001), however there was no association between VO<inf>2peak</inf> and HRV (standard deviation of the N-N interval). This lack of association remained when an SDNN and diabetes interaction was included in the model. CONCLUSIONS: CKD patients with diabetes have worsened heart rate variability and cardiorespiratory fitness compared to those without diabetes. However, there is no association between heart rate variability and cardiorespiratory fitness, regardless of diabetes status. Future research should investigate other pathological systems which may be contributing to reduced cardiorespiratory fitness in the CKD population.