Type 1 Diabetes Duration Decreases Pulmonary Diffusing Capacity during Exercise

Background: Diabetes damages peripheral tissues; however, its effects on the lung are less known. Lung diffusing capacity (DLCO) is influenced by alveolar-capillary membrane conductance (DM) and pulmonary capillary blood volume (VC), both of which are reduced in adults with type 1 diabetes (T1D). Objective: We sought to determine if diabetes duration affects DLCO, DM, VC, and cardiac output (Q). Methods: 24 T1D patients (10.7-52.8 years) and 24 non-diabetic controls were recruited and had DLCO, DM, VC, and Q measured at rest and during exercise (40, 70 and 90% VO₂max). Results: When stratified into two groups based on age (young, <20.6 years old), there were no significant differences in DLCO, DM, VC, or Q (all of which were normalized to body surface area [BSA]) in the young group or in the old group. When stratified by diabetes duration (short duration, 0.33-8.9 years vs. long duration, 9.6-28 years), the T1D patients in the long duration group had lower DLCO/BSA and DM/BSA compared to the controls (p < 0.05). There were no differences in any of the variables in the short duration group. Conclusions: This study has shown that duration of diabetes is associated with decrements in diffusing capacity and its components.