Diabetes affects over 18.2 million individuals in the United States alone. Current therapy to treat type 1 diabetes relies on subcutaneous insulin administration either by injection or continuous infusion. In addition, patients with type 2 diabetes who fail lifestyle intervention and oral therapy require subcutaneous insulin. Optimal injection protocols to achieve tight metabolic control often prove burdensome to patients. Thus, development of pulmonary insulin delivery to supplement and/or replace subcutaneous insulin injections may be an effective alternative, allowing patients to achieve intensive diabetes management. This review will discuss the devices in development for the delivery of inhaled insulin. In addition, the efficacy of inhaled insulin in both type 1 and type 2 diabetic populations will be discussed. Finally, the available safety data with respect to the unique pulmonary effects of inhaled insulin will be covered.