A rapid-acting dry-powder inhaled insulin (Exubera), an alternative to injected insulin, currently is being reviewed by the FDA. In this industry-sponsored multicenter trial, 145 patients whose type 2 diabetes was not controlled adequately by diet and exercise alone were randomized to receive either inhaled insulin (given before each meal, with dose adjustments as needed) or rosiglitazone (4 mg twice daily). Mean age of enrolled patients was 54, and mean baseline hemoglobin A1c level was 9.5%.
After 3 months of treatment, the primary endpoint (HbA1c level lower than 8%) was reached by 83% of inhaled-insulin recipients and 58% of rosiglitazone recipients — a significant difference. However, hypoglycemic episodes occurred significantly more often in the inhaled-insulin group than in the rosiglitazone group (0.7 vs. 0.05 episodes per patient-month); none of these episodes was severe.
In this study, pre-meal inhaled insulin lowered HbA1c levels more effectively than oral therapy with rosiglitazone. However, the relatively frequent occurrence of hypoglycemia with inhaled insulin suggests that accurate dosing can be an issue for some patients. Other aspects of inhaled insulin therapy that are being studied include development of insulin antibodies and changes in pulmonary function with long-term use. If inhaled insulin is approved by the FDA, it will represent another therapeutic option for patients with type 2 diabetes, but primary care physicians will need guidance in selecting appropriate candidates for the drug.
Reference:
DeFronzo RA et al. Efficacy of inhaled insulin in patients with type 2 diabetes not controlled with diet and exercise: A 12-week, randomized, comparative trial. Diabetes Care 2005 Aug; 28:1922-8.