Impaired glucose regulation in heart failure: impact of exercise therapy

Heart failure (HF) is one of the most important causes of morbidity and mortality in the Western world. Despite advances in medical therapy for cardiac patients in general, the prognosis for HF patients is still poor. Moreover, many patients with chronic HF are believed to have unrecognized diabetes, which is associated with a worse prognosis. In this thesis, the prevalence and characteristics of impaired glucose regulation, as well as the impact of exercise therapy on glucose regulation were studied in HF. We found evidence that the prevalence of impaired glucose regulation is severely increased in acute as well as chronic HF patients. It was demonstrated that from 98 patients hospitalized for acute HF, only a nonsignificant proportion (1%) presented with a normal glucose profile on the day of hospital discharge. Furthermore, our results showed that from all glycaemic markers, increased fasting blood glucose and HbA1c concentrations contain little prognostic value, while impaired glucose tolerance was the better predictor for morbidity (cardiorenal events) and mortality (chapter 3). In a second observational study, the majority (80%) of 56 patients with stable chronic HF (without diagnosed diabetes) presented with an abnormal glucose regulation (chapter 4). In acute and chronic HF patients, oral glucose tolerance testing was more efficient to detect significantly impaired glucose regulation compared to fasting glucose and HbA1c concentrations (chapter 3-4). In the investigation of the relation between impaired glucose regulation and possible explanatory parameters in chronic HF patients, glucose tolerance was associated with echocardiographic measures of ventricular filling pressures, but not with measures of systolic function nor cardiac dimensions. Furthermore, we found that increased waist-tohip fat ratio was a predictor of impaired glucose regulation. Muscle function also seemed to be associated with glucose regulation, but this finding needs further research (chapter 4). Available literature and official guidelines do not provide effective therapies to improve glucose regulation in HF patients. Therefore, the impact of exercise training on glucose regulation in HF was investigated in an animal model for HF (chapter 5) and in stable chronic HF patients (chapter 6). The exercise interventions used in both experiments were able to reduce insulin release during oral glucose tolerance testing, while glucose responses remained unaltered. In stable chronic HF patients, exercise-induced changes in insulin release were associated with changes in waist-to-hip fat mass ratio (chapter 6). These findings are clinically relevant because they may lead to a more comprehensive evaluation of glucose tolerance in acute and chronic HF settings. Furthermore, they can lead to a better understanding of the prognostic impact and of the factors associated with impaired glucose regulation in HF patients. In addition, our findings support more intensive promotion of physical activity for HF patients in order to improve glucose regulation.

Publication year:2014

Accessibility:Open