Exercise tolerance and ventilatory response in patients with type-1 diabetes

Introduction: Physical activity is an effective therapeutic tool for pulmonary and cardiovascular risk prevention in patients with type-1 diabetes mellitus (T1DM). However, such intervention might be negatively affected by a reduced exercise tolerance in T1DM patients (Komatsu et al, Pediatric Diabetes 2005, 6:145–149). Aim of the study: To assess if impaired exercise tolerance in T1DM is related to an altered ventilatory response. Methods: Seventeen T1DM patients (basal-bolus treatment, 18-45 years, diabetes history Results: Mean oxygen uptake at peak exercise (V9O2,peak) was significantly lower in T1DM subjects (2200 ± 132ml/min) than healthy subjects (2659 ± 120 ml/min p = 0.035). There were no statistically significant differences in ventilatory response (i.e. SatO2 and Borg score at baseline and peak, BR, VE/VCO2 slope) between the two groups. However, the respiratory exchange ratio (RER) and lactate levels were significantly lower in T1DM subjects at peak exercise (1.3±0.04 vs 1.1±0.03, p= 0.02 and and 4.0±0.3 mmol/l vs 5.6±0.5 mmol/l, p = 0.02, respectively). Conclusions: Patients affected by T1DM confirmed a reduced exercise tolerance than normal subjects. No difference in the ventilatory response was detected. Interestingly, though, T1DM subjects showed a different pattern in O2 consumption and CO2 production, possibly due to an increased use of lipid substrates with an impaired carbohydrate metabolism.