Background: Despite demonstrated benefits, intensive insulin therapy has not gained widespread clinical acceptance for several reasons: Multiple daily injections are inconvenient, adherence is a concern, and the time-activity profile may not mimic normal insulin secretion. As such, alternate means of administering insulin are being evaluated.
Objective: To assess the efficacy and safety of pulmonary delivery of insulin in type 2 diabetic patients who require insulin.
Design: Randomized, open-label, 3-month study consisting of a screening visit, a 4-week baseline lead-in phase, and a 12-week treatment phase.
Setting: General clinical research center and outpatient research clinics.
Patients: 26 patients (16 men, 10 women) with type 2 diabetes (average age, 51.1 years; average duration of diabetes, 11.2 years).
Intervention: Patients received inhaled insulin before each meal plus a bedtime injection of ultralente insulin, performed home glucose monitoring, and had weekly adjustment of insulin dose; target level for preprandial plasma glucose was 5.55 to 8.88 mmol/L (100 to 160 mg/dL).
Measurements: Glycemic control (hemoglobin A1c level) obtained at baseline and monthly for 3 months. Pulmonary function tests were done at baseline and at the end of the study.
Results: Inhaled insulin treatment for 3 months significantly improved glycemic control compared with baseline: Mean hemoglobin A1c levels decreased by 0.0071 ± 0.0072 (0.71% ± 0.72%). Patients experienced an average of 0.83 mild to moderate hypoglycemic event per month; no severe events were recorded. Patients showed no significant weight gain or change in pulmonary function compared with baseline.
Conclusions: Pulmonary delivery of insulin in type 2 diabetic patients who require insulin improved glycemic control, was well tolerated, and demonstrated no adverse pulmonary effects. Larger-scale studies are ongoing to provide long-term efficacy and safety data.
*For members of the Inhaled Insulin Study Group, see Appendix.