Differences in cardiorespiratory fitness in obese and non-obese patients with type 2 diabetes

Introduction:

Cardiopulmonary exercise testing (CPX) is used clinically to determine overall cardiovascular fitness. Of the metrics collected from CPX, peak oxygen uptake (peak VO₂) is the strongest predictor of fitness and prognosis. The goal of this study was to examine differences in peak VO₂ between obese and non-obese patients with T2DM.

Methods:

This retrospective study included sedentary patients with a history of T2DM without the presence of other cardiovascular disease. All patients performed individual ramp CPX to volitional exhaustion. Respiratory data were collected breath by breath and analyzed using 30 s rolling averages listed every 10 s. Peak VO₂, calculated as the highest 30 s averaged value taken at the end of the exercise phase, was compared between obese (BMI ≥30 kg/m²) and non-obese (BMI < 30 kg/m²) patients.

Results:

61 patients (28 female [46%]; 60 ± 11 y; 29.8 ± 6.7 kg/m²) participated in the study. Patients with T2DM and obesity achieved significantly lower peak VO₂ relative to body weight compared to the non-obese. This was true for men (25.2 ± 4.7 ml/kg/min vs. 32.5 ± 8.0 ml/kg/min, p< 0.01) and women (19.1 ± 3.0 ml/kg/min vs. 23.8 ± 4.7 ml/kg/min, p< 0.01), with significantly higher peak VO₂ observed in men. Absolute peak VO₂ (L/min) was not significantly different between the groups.

Conclusion:

Patients with T2DM and obesity have lower cardiorespiratory fitness than those with normal weight. Future studies will need to further evaluate the poor prognosis associated with a low peak VO2 in patients with concomitant diabetes and obesity.