Polymer-Based Delivery of Peptide Drugs to Treat Diabetes: Normalizing Hyperglycemia and Preventing Diabetic Complications

Diabetes is a serious metabolic disease in which chronic hyperglycemia results in diabetic microvascular and macrovascular complications from progressive vascular damage and dysfunction. Diabetes is life-threating and disabling, and is associated with costly complications and reduced life expectancy. Therefore, developing therapies for the treatment of diabetes is urgent and a significant challenge. Several peptides, including insulin, glucagon-like peptide-1, proinsulin C-peptide, and apelin, effectively normalize hyperglycemia and prevent hyperglycemia-induced diabetic complications, which are essential for the treatment of diabetes. However, a key limitation of peptide drugs for the clinical use is their short half-life. In this review, we describe the pathophysiological mechanisms and treatments of diabetic vascular complications. In addition, we discuss modification of peptide drugs by various approaches involving polymers to extend their blood circulating times and the use of the modified peptides in experimental and clinical studies.