Physical fitness and exercise endurance measured by oxygen uptake kinetics in patients with type 2 diabetes mellitus

Abstract

Exercise testing was used to examine 38 type 2 diabetes mellitus (DM) patients without cardiovascular complications, aged 47-74 years (body mass index [BMI], 23.8+ 1.6kg/m2), and 18 healthy volunteers, aged 45-68 years (BMI, 22.5 ± 1.5 kg/m2). A graded cycling exercise test was performed, monitoring gas exchange to evaluate physical fitness and exercise endurance by oxygen uptake (VO2) kinetics. The following results were obtained. (1) Oxygen deficit (02deficit) and time constant (τ on) at the onset of exercise were significantly higher in subjects with type 2 DM compared with controls (p<0.01). (2) Maximum oxygen uptake (VO2max) and maximum work load were lower by 12% and 15%, respectively (p<0.05). These data suggest a notable abnormality in the cardiopulmonary response at the onset of exercise and a lower exercise endurance in subjects with type 2 DM. These findings may reflect impaired cardiac response to exercise, although an additional defect in skeletal muscle oxygen diffusion or oxygen utilization is also possible.