Syringe, pen, inhaler - the evolution of insulin therapy.

The therapy with inhalable insulin can be expected to change the present concepts and the market of subcutaneous insulin dramatically within the next years. Several companies are currently developing formulations of inhalable insulin. In the most advanced concept, insulin is delivered as a dry-powder insulin formulation via a special aerosol device system. The phase III studies evaluating the efficiency of the inhaled insulin are already on their way. The recent phase II studies have shown, that the lung is capable of absorbing new insulin formulation in a dose-dependent and reproducible manner. 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 subcutaneous insulin treatment regimens. The most important advantage of the new therapy is the enhanced therapeutic comfort 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 comparison to an intensified conventional insulin therapy. However, before a large-scale marketing, several open questions have to be carefully investigated, the most important being the possible long-term effects of insulin inhalation for the lung, since insulin is known to have growth-promoting properties. There is still no available clinical data concerning the efficiency of the inhaled insulin in patients with pulmonary diseases which may cause problems in absorption of inhaled insulin due to the smaller cumulative alveolar surface. In smokers without pulmonary disease seems the inhaled insulin to act stronger and faster. Since therapy with inhalable insulin requires larger doses of insulin in comparison to subcutaneous insulin to achieve the same systemic effect, the costs of this therapy need to be clarified, too.