Attempts to develop the lungs as a route for the delivery of insulin began as early as the 1920s. But inhalers that could deliver insulin via the lungs in a clinically viable manner were not developed until the 1990s. The lungs offer a large surface area of 100 m² to 140 m² (roughly the size of a tennis court) for the absorption of inhaled insulin. Moreover, the very thin alveolar-capillary barrier on the surface of the lungs allows for rapid uptake of insulin into the blood, similar to that seen with the rapid-acting insulin analogues – or even faster. Jay Skyler brings us up to date with the latest developments in this potential alternative to subcutaneous insulin.