Inhaled insulin seemed like a great idea the first time around because everybody liked the idea of not having to give injections every day. It seemed especially promising for use in children or those with a phobia of needles. It sounded like it would be easier to administer than injections which required alcohol swabs, sharps containers, and a certain amount of privacy.
Exubera™ came to market over 10 years ago but sales of the product never really took off. It required a large device to aerosolize the insulin, the dosing was not as flexible as with injectable insulin, and it turned out to have some concerning pulmonary side effects, including declining lung function and a possible link to lung cancer. It had to be used in conjunction with long-acting injectable insulin, so patients still needed injections. The product was withdrawn from the market within 2 years.
In 2014, another inhaled insulin called Afrezza™ was approved by the FDA. This one appeared to have some advantages over its predecessor, such as a smaller device and easier to convert dosing. But the concerns about lung problems persisted. Introducing insulin which has growth factor properties directly into lung tissue could increase the risk of lung cancer. Although clinical trials have not been large enough to determine cause and effect, this is worrisome for patients and prescribers alike.
With several new injectable insulins becoming available in the last few years, patients have several options available, and the future of inhaled insulin is unclear. Patients with severe needle phobia seem to be the most likely market for this product.
Other non-injectable options may be coming, though. See my post on oral insulin.