Gels for constant and smart delivery of insulin

The focus of this review is the role of gelatinous materials for oral, transdermal and peritoneal insulin platforms as alternatives to the ubiquitous subcutaneous depot approach. Hydrogels that form hydrated, cohesive materials and the topologically complex micellar types can add ligand interaction, bond vulnerability and rheological characteristics to develop reliable programmed release, including closed loop (automated basal and bolus) activity in non-oral routes. In addition, the potential protection of the protein and likely increased paracellular uptake mean that orally active insulin is feasible. While unlikely to be suitable for closed loop delivery, the driver for gut absorption is not only to increase the convenience and decrease dosage trauma, but to target the mesentery-portal vasculature rather than peripheral tissue, thus improving hepatic glycogen equilibrium and reducing the obesogenic effect and hypoglycaemic episodes.