Lung diffusing capacity (DLCO) is influenced by alveolar-capillary membrane conductance (DM) and pulmonary capillary blood volume (V C), both of which can be impaired in sedentary type 1 diabetes mellitus (T1DM) subjects due to hyperglycemia. We sought to determine if T1DM, and glycemic control, affected DLNO, DLCO, DM, VC and SaO2 during maximal exercise in aerobically fit T1DM subjects. We recruited 12 T1DM subjects and 18 non-diabetic subjects measuring DLNO, DLCO, DM, and VC along with SaO2 and cardiac output (Q) at peak exercise. The T1DM subjects had significantly lower DLCO/Q and DM/Q with no difference in Q, DLNO, DLCO, DM, or V C (DLCO/Q = 2.1 ± 0.4 vs. 1.7 ± 0.3, DM/Q = 2.8 ± 0.6 vs. 2.4 ± 0.5, non-diabetic and T1DM, p < 0.05). In addition, when considering all subjects there was a relationship between DLCO/Q and SaO2 at peak exercise (r = 0.46, p = 0.01). Within the T1DM group, the optimal glycemic control group (HbA1c <7%, n = 6) had higher DLNO, DLCO, and DM/Q than the poor glycemic control subjects (HbA1c ≥7%, n = 6) at peak exercise (DLCO = 38.3 ± 8.0 vs. 28.5 ± 6.9 ml/min/mmHg, DLNO = 120.3 ± 24.3 vs. 89.1 ± 21.0 ml/min/mmHg, DM/Q = 3.8 ± 0.8 vs. 2.7 ± 0.2, optimal vs. poor control, p < 0.05). There was a negative correlation between HbA1c with DLCO, DM and DM/Q at peak exercise (DLCO: r = -0.70, p = 0.01; DM: r = -0.70, p = 0.01; DM/Q: r = -0.68, p = 0.02). These results demonstrate that there is a reduction in lung diffusing capacity in aerobically fit athletes with T1DM at peak exercise, but suggests that maintaining near-normoglycemia potentially averts lung diffusion impairments.
- Alveolar-capillary membrane conductance
- Lung diffusion
- Oxygen saturation
- Pulmonary capillary blood volume