Intersession Variability in Single-Breath Diffusing Capacity in Diabetics without Overt Lung Disease

Rationale: American Thoracic Society guidelines state that a 10% or greater intersession change in diffusing capacity of the lung (DlCO) should be considered clinically significant. However, little is known about the short-term intersession variability in DlCO in untrained subjects or how variability is affected by rigorous external quality control.Objectives: To characterize the intersession variability of DlCO and the effect of different quality control methods in untrained individuals without significant lung disease.Methods: Data were pooled from the comparator arms of 14 preregistration trials of inhaled insulin that included nonsmoking diabetic patients without significant lung disease. A total of 699 participants performed repeated DlCO measurements using a highly standardized technique. A total of 948 participants performed repeated measurements using routine clinical testing.Measurements and Main Results: The mean intersession absolute change in DlCO using the highly standardized method was 1.45 ...