An injectable and biodegradable zwitterionic gel for extending the longevity and performance of insulin infusion catheters.

Continuous subcutaneous insulin infusion (CSII) is an essential insulin replacement therapy in the management of diabetes. However, the longevity of clinical CSII is limited by skin complications, by impaired insulin absorption and by occlusions associated with the subcutaneous insertion of CSII catheters, which require replacement and rotation of the insertion site every few days. Here we show that a biodegradable zwitterionic gel covering the tip end of commercial off-the-shelf CSII catheters fully resolves early skin irritations, extends the longevity of catheters and improves the rate of insulin absorption (also with respect to conventional syringe-based subcutaneous injection) for longer than 6 months in diabetic mice, and by 11 days in diabetic minipigs (from 2 to 13 days, under standard CSII-wearing conditions of insulin pump therapy and in a continuous basal-plus-bolus-infusion setting). The implanted gel displayed anti-inflammatory and anti-foreign-body-reaction properties and promoted the local formation of new blood vessels. The gel is subcutaneously injected before the tip of catheter is inserted into it, and should be generally applicable to CSII catheters and other implantable devices.