Effect of type 2 diabetes mellitus on exercise intolerance and the physiological responses to exercise in peripheral arterial disease

Aims/hypothesis: There are conflicting data about the effect of type 2 diabetes mellitus on exercise tolerance in peripheral arterial disease. To elucidate this problem, we compared the tolerance and physiological responses to treadmill and cycle exercise in 31 patients with peripheral arterial disease and intermittent claudication. Materials and methods: One group of these patients had type 2 diabetes (n=12) and its members were matched for sex and age with a group of patients who did not have diabetes (n=12). Since BMI and body weight were greater in the diabetic group (28.4±3.7 vs 25.2±2.4 kg/m²; 84.0±14.6 vs 73.8±8.0 kg), we also studied a third, 'heavy' group of non-diabetic patients with claudication of similar age (n=7; BMI = 30.9±5.3 kg/m²; body weight = 85.2±8.2 kg). Results: Compared with the 'light' non-diabetic group, maximum treadmill times were shorter for the diabetic and heavy non-diabetic groups (1,448 vs 845 and 915 s; ANOVA p=0.01); maximum cycle time also tended to be shorter (ANOVA, p=0.08) in the diabetic and heavy non-diabetic groups (median = 1,231 vs 730 and 797 s). The majority of physiological responses assessed were not different between the groups, although the time constant of oxygen uptake during submaximal treadmill and cycle exercise was significantly larger (ANOVA p<0.05) for the diabetic group. Conclusions/interpretation: These data demonstrate that exercise tolerance is lower in diabetic than non-diabetic patients with claudication, but that this difference is due to obesity rather than diabetes itself.