Long-term tolerability of inhaled human insulin (Exubera^®) in patients with poorly controlled type 2 diabetes

Objective: Inhaled human insulin (Exubera^®; EXU) has shown encouraging tolerability in short-term trials. We evaluated the safety profile of EXU after long-term exposure.

Design: In two, open-label, 2-year studies patients poorly controlled on a sulphonylurea were randomised to adjunctive EXU or metformin (study 1) and patients poorly controlled on metformin were randomised to adjunctive EXU or the sulphonylurea, glibenclamide (study 2).

Patients: The studies included 446 (study 1) and 476 (study 2) patients with type 2 diabetes, no clinically significant respiratory disease and glycosylated haemoglobin (HbA_1c) levels of 8–12%.

Measurements: Main outcome measures were pulmonary function tests and insulin antibody assays.

Results: A total of 109 patients (study 1) and 195 patients (study 2) completed 104 weeks treatment. In both studies, small treatment group differences in change from baseline forced expiratory volume in 1 s were greatest at 6 months (first time-point measured) and less at later visits, and reversed on treatment discontinuation. At 2 years, differences in mean changes were −0.10 and −0.01 l in studies 1 and 2, respectively, and −0.04 l for the pooled studies. There was no discernable effect of long-term EXU therapy on pulmonary gas exchange. Insulin antibody binding reached a plateau at 6 months and did not correlate with HbA_1c or lung function changes. Glycaemic control was maintained over 2 years.

Conclusions: Exubera was well tolerated during long-term use. Pulmonary function changes compared with comparator groups were small, non-progressive and reversed upon treatment discontinuation. Importantly, rates of lung function change were indistinguishable between EXU and comparator after 6 months of therapy.