Abstract
Optimal coverage of insulin needs is the paramount aim of insulin replacement therapy in patients with diabetes mellitus. To apply insulin without breaking the skin barrier by a needle and/or to allow a more physiological provision of insulin are the main reasons triggering the continuous search for alternative routes of insulin administration. Despite numerous attempts over the past 9 decades to develop an insulin pill, no insulin for oral dosing is commercially available. By way of a structured approach, we aim to provide a systematic update on the most recent developments toward an orally available insulin formulation with a clear focus on data from clinical-experimental and clinical studies. Thirteen companies that claim to be working on oral insulin formulations were identified. However, only 6 of these companies published new clinical trial results within the past 5 years. Interestingly, these clinical data reports make up a mere 4% of the considerably high total number of publications on the development of oral insulin formulations within this time period. While this picture clearly reflects the rising research interest in orally bioavailable insulin formulations, it also highlights the fact that the lion's share of research efforts is still allocated to the preclinical stages.