Role of Insulin in the Type 2 Diabetes Therapy: Past, Present and Future

Since 2006 a relevant number of therapeutical algorithms for the management of type 2 diabetes have been proposed, generating a lively debate in the scientific community, particularly on the ideal timing for introduction of insulin therapy and on which drug should be preferred as add-on therapy in patients failing to metformin. At the moment, there is no real consensus. The aim of the present review is to summarize established knowledge and areas for debate with respect to insulin therapy in type 2 diabetes. In type 2 diabetic patients, insulin represents a therapy with a long and well-established history, but, considering the modern insulin therapy, several points must be carefully examined. The role played by the introduction of insulin analogues, the choice of insulin regimens, the ongoing debate on insulin and cancer, the cardiovascular effects of insulin, the role of insulin on β-cell protection and the actual clinical perspective in the treatment of the disease. Nevertheless, still many exciting expectations exist: the new insulin analogues, the technological options, the inhaled and oral insulin and the issue of transplantation. Although insulin is the more potent hypoglicemic agent, the availability of a wider spectrum of therapeutic agents, many of which are better tolerated than insulin, has reduced the field of application for insulin treatment; presently, insulin is used only in those who cannot maintain an adequate glycemic control with other drugs. Furthermore, a lively research activity is currently ongoing, in order to make insulin therapy even safer and simpler for patients.