Methods: Cardiopulmonary exercise and glycaemic control tests were retrospectively analysed in 46 adults with CF (age: 26.9 y [range: 16.3–66.5 y]; forced expiratory volume in 1s: 65.3% [range: 26.8–105.7%]; 26 males), diagnosed with CFRD (n = 19), impaired glucose tolerance (IGT; n = 8) or normal glucose tolerance (NGT; n = 19).
Results: Maximal oxygen uptake (V ̇O2max) was reduced in adults with IGT and CFRD compared to their age- and gender-matched counterparts with NGT (p < 0.05); however, there was no difference when lung function was included as a covariate (all p > 0.05). V ̇O2max was greater in adults who experienced post-reactive hypoglycaemia vs. NGT without hypoglycaemia (p < 0.05). The frequency of ventilatory limitation (84%, 63% and 37%, respectively; p < 0.05) but not ventilation-perfusion mismatch (42%, 38% and 16%, respectively; p > 0.05), was greater with CFRD and IGT vs. NGT. There was also no difference in arterial oxygen saturation changes between groups (p > 0.05). Gender and body mass index were significant predictors of V ̇O2max (adjusted R2 = 0.37, p < 0.01), but glycaemic control did not explain additional variance (p > 0.05).
Conclusions: Adults with CF-related dysglycaemia had a reduced V ̇O2max compared to age- and gender-matched counterparts, due to a greater degree of CF lung disease in these populations.
- cardiorespiratory fitness
- cystic fibrosis-related diabetes
- maximal oxygen uptake
- respiratory disease