The therapy with inhalable insulin can be expected to change the presentconcepts and the market of subcutaneous insulin dramatically within the next years. Several companiesare currently developing formulations of inhalable insulin. In the most advanced concept, insulin isdelivered as a dry-powder insulin formulation via a special aerosol device system. The phase III studiesevaluating the efficiency of the inhaled insulin are already on their way. The recent phase II studieshave shown, that the lung is capable of absorbing new insulin formulation in a dose-dependent and reproduciblemanner. However, a relatively small number of diabetic patients have been included in these studies,yet. The therapeutic efficacy and safety of the inhaled insulin is comparable to that of the usual subcutaneousinsulin treatment regimens. The most important advantage of the new therapy is the enhanced therapeuticcomfort of the patient who does not need to inject insulin for meal time glucose control. Generally,in terms of glycemic control, inhalable insulin offers no advantages in type 1 diabetics in comparisonto an intensified conventional insulin therapy. However, before a large-scale marketing, several openquestions have to be carefully investigated, the most important being the possible long-term effectsof insulin inhalation for the lung, since insulin is known to have growth-promoting properties. Thereis still no available clinical data concerning the efficiency of the inhaled insulin in patients withpulmonary diseases which may cause problems in absorption of inhaled insulin due to the smaller cumulativealveolar surface. In smokers without pulmonary disease seems the inhaled insulin to act stronger andfaster. Since therapy with inhalable insulin requires larger doses of insulin in comparison to subcutaneousinsulin to achieve the same systemic effect, the costs of this therapy need to be clarified, too.

Keywords: inhaled insulin, lung function, fibrogenesis, Diabetes Mellitus, alveoles