Many patients with type 1 or type 2 diabetes mellitus (DM) do not achieve recommended glycemic goals. Insulin therapy is often delayed, despite its effectiveness in maintaining glycemic control, for reasons such as fear of needles or dislike of the complexity of injections. Inhaled dry powder insulin (IDPI) is approved for preprandial use in both the United States and Europe.Relevant English-language publications were identified through a search of the PubMed data-base (1980-2007). Search terms included diabetes, in combination with subcutaneous and/or inhaled insulin. A similar search of abstracts from the 2006 American Diabetes Association 66th Annual Scientific Sessions was also performed.Eight clinical studies to date have reported that IDPI consistently improved glycemic control, whether used in combination with longer-acting SC insulin regimens in patients with type 1 or type 2 DM or to supplement or replace oral agent therapy in patients with type 2 DM. Evidence to date suggests that IDPI is associated with an acceptable tolerability profile, with a risk of hypoglycemia similar to that of SC insulin (risk ratios in 2 studies were 0.94 and 0.96, in favor of IDPI). Moreover, no clinically significant changes in pulmonary function have been noted. Patients treated with IDPI in clinical studies reported significantly greater improvements in overall satisfaction with treatment compared with SC insulin (P < 0.01) or oral agent therapy (P= 0.02).IDPI is effective and well tolerated for the treatment of diabetes and may be an option for patients to achieve glycemic control.