Advanced Polymeric Nanoparticles for Sustained Insulin Delivery in Type 1 Diabetes

Type 1 diabetes necessitates life-long insulin replacement, but current delivery systems rely on insulin injections, which are not always absorbed, patients are not always able to adhere to the therapy and recreating the physiological insulin secretion is impossible. Polymeric nanoparticles have taken the place of insulin as potential prolonged carriers for insulin delivery due to their ability to protect insulin against degradation, enhance bioavailability, and control release by diffusion, polymer degradation, swelling, and glucose-responsive release. This review summarizes recent progress in polymeric nanoparticle systems for insulin delivery, with emphasis on polymer selection, formulation strategies, release mechanisms, and routes of administration, including oral, subcutaneous, transdermal, and intranasal pathways. Natural, synthetic, and hybrid polymers have all demonstrated value in improving insulin encapsulation and therapeutic performance. Advances in fabrication techniques such as double emulsion, ionic gelation, nanoprecipitation, and microfluidic preparation have further strengthened the potential of these systems. Despite encouraging progress, important translational barriers remain, including limited oral bioavailability, formulation instability, scale-up challenges, reproducibility issues, and incomplete long-term safety data. Overall, polymeric nanoparticles represent a versatile and evolving platform that may improve glycemic control and reduce treatment burden in type 1 diabetes, but successful clinical application will require standardized characterization, robust in vivo validation, and scalable, patient-acceptable designs.