Exercise gas exchange patterns in diabetes : evidence from the EURO(pean) EX(ercise) population-based study

Introduction: Diabetes mellitus (DM) is a risk condition that may determine exercise limitation and reduced oxygen consumption (VO2). Hypothesis: 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 may help to better define cardiovascular (CV) risk and to improve the timing of therapeutic interventions. Methods: 442 asymptomatic subjects enrolled in the EURO EX trial, (mean age 60±14 years; male 49.3%; BMI 28±5.5 kg/m2) with different CV risk factors (hypertension 66%, dyslipidemia 50.2%, smoking habit 19.2%, diabetes 15.4%) underwent a maximal CPET with personalized ramp protocol. Results: The population was divided into two groups according to the presence of diabetes. Diabetic subjects (n=68) were significantly older than non-DM subjects and showed a significant lower VO2 at peak exercise (16.3±4.1 vs 19.9±7.4 ml/kg/min), a steeper VE/VCO2 slope (27±3.7 vs 25.7±4) and an impaired heart rarte reserve (peak HR 123±27 vs 135±22 bpm) and recovery (HRR 12±6 vs 17±11 beats) and higher systolic blood pressure (SBP) at rest (142±22 vs 132±15 mmHg) and peak exercise (193±20 vs 184±22 mmHg). A significant difference in the VE/VCO2 slope, peak O2 pulse, SBP at rest and ΔVO2/ΔWR slope was maintained when a correction for confounding factors (BMI, age, gender, prevalence of dyslipidemia and hypertension) was applied. Conclusions: Asymptomatic DM subjects with normal left ventricular function compared to non-diabetics show a reduced HRR and peak O2 pulse, an increased VE/VCO2 slope and higher SBP as a typical phenotype. These findings suggest that an impaired sympathovagal control may play a key role. Whether assessment of these variables may improve the risk-related definition and a timely metabolic control in this patients seems to be worth of further investigation.