As a result of knowledge gained from the management of asthma with inhalers and nebulisers, pulmonary delivery devices for insulin have been developed. Particle size of the aerosol particularly influences drug delivery. Although several pharmaceutical companies are developing different systems, Pfizer have launched the first inhaled insulin (Exubera). Clinical trials have taken place in patients with both type 1 and type 2 diabetes, but have shown similar glucose control as subcutaneous insulin delivery. However, patient satisfaction does seem to be increased in patients taking inhaled insulins. Further studies are needed to investigate compliance, side-effect profiles, quality of life, long-term glycaemia control and cost effectiveness.