Exercise Gas Exchange Phenotypes in Diabetic Subjects : Findings From the EURO(pean) EX(ercise) Population-Based Study

Background: Diabetes mellitus (DM) is a risk condition that may determine overall exercise limitation and reduced oxygen consumption (VO2). No study in literature has addressed the cardiopulmonary exercise testing (CPET) phenotype in diabetic subjects with normal left ventricular function. Their functional characterization by expired gas analysis could help to better define cardiovascular (CV) risk and improving the timing of therapeutic interventions. Methods: 318 asymptomatic subjects (mean age 59±14 years; male 48.4%; BMI 28±6 kg/m2) with different CV risk factors (hypertension 66%, dyslipidemia 49%, smoking 22%, diabetes 14%) underwent a maximal CPET with personalized ramp protocol. Results: The population was divided into two groups according to the presence of diabetes among CV risk factors. Diabetic subjects (n=43) showed a significant lower VO2 at peak exercise (16.8±4.2 vs 20.1±7.3 ml/kg/min), a steeper VE/VCO2 slope (26.9±3.5 vs 25.3±3.7) and a reduced heart rate recovery HRR (13±7 vs 17±12 bpm). No other CPET-derived variables were found to significantly differ. No DM DM Variables (n=275) (n=43) P value Age (y) 58±14 67±11 0.005 Male (%) 47.3 55.8 ns BMI (kg/m2) 28±6 29±5 ns Peak VO2 (ml/kg/min) 20.1±7.3 16.8±4.2 0.004 VE/VCO2 slope 25.3±3.7 26.9±3.5 0.005 HRR (bpm) 17±12 13±7 0.019 Delta VO2/delta WR 9.5±1.5 9.7±2 ns Conclusions: DM subjects with normal left ventricular function compared to non-diabetics show a reduced HRR and an increased VE/VCO2 slope as a typical phenotype suggestive a key sympathovagal control imbalance. Whether assessment of these variables may improve the risk-related definition and a timely metabolic control seems to be worth of further investigation.