Objective: To assess pulmonary safety during discontinuation and readministration of inhaled human insulin (EXU; Exubera((R)) insulin human [rDNA origin]) Inhalation Powder) therapy in adults with type 1 diabetes.
Methods: Patients were randomized to receive basal insulin plus either pre-meal EXU (n=290) or a short-acting subcutaneous (SC) insulin (n=290) for 2 years (comparative phase), followed by 6 months of SC insulin (washout) and 6 months of their original therapy (readministration). Highly standardized lung function tests were performed throughout.
Results: Small treatment group differences favoring SC insulin in change from baseline forced expiratory volume in 1s (FEV(1)) and carbon monoxide diffusing capacity (DL(CO)) occurred early and were non-progressive. These differences resolved during washout and recurred at the same magnitude during readministration. Both groups maintained glycemic control, and hypoglycemic event rates were similar. In the EXU group, insulin antibody (IAb) levels plateaued at 12 months, declined to near baseline levels during washout and increased during readministration to levels observed in the comparative phase.
Conclusions: FEV(1) and DL(CO) changes observed during discontinuation and readministration of EXU therapy are consistent with a reversible, non-progressive and non-pathological effect on lung function. EXU readministration is not associated with an augmented IAb response.