PROJECT SUMMARY The ultimate goal of the proposed work is to develop a novel co-formulation of insulin analogues (e.g. lispro and aspart) with an amylin analogue (e.g. pramlintide) and with incretin hormones (e.g. liraglutide), to enable a transformational new treatment for diabetes constituting a true replacement therapy. The most challenging aspect of optimal glycemic control for the 1.45 million people with type 1 diabetes (T1D) in the United States is limiting large increases in blood glucose after a meal. People with type 1 diabetes do not produce the insulin required for the body to process glucose, so insulin must be replaced by daily injections. Amylin is a small peptide hormone excreted alongside insulin by pancreatic β islet cells that acts centrally to slow gastric emptying, suppress postprandial glucagon secretion, and decrease food intake, thus complementing the action of insulin to regulate blood glucose levels. Similar to insulin, amylin production is completely absent in individuals with type 1 diabetes on account of their lack of pancreatic β cells. T1D is also characterized by abnormal suppression of glucagon secretion in response to hyperglycemia. Glucagon-like peptide-1 (GLP-1) is an incretin hormone and neurotransmitter secreted from intestinal L-cells in response to nutrients to stimulate insulin and suppress glucagon secretion in a glucose-dependent manner. Long-acting GLP-1 receptor agonists (GLP-1 RAs) have become central to the treatment of diabetes and while these drugs are not yet approved for T1D patients, GLP-1 RAs appear to be well tolerated in patients with T1D and could have beneficial effects in both new onset and longstanding T1D patients. As an adjunctive therapy to insulin, GLP-1 RAs can improve glycemic control and body weight in longstanding disease while also reducing insulin requirements in T1D patients. Current administration regimens for these therapeutics are highly burdensome as they must be injected either daily or weekly or taken daily orally. A true replacement therapy, therefore, would administer both amylin and insulin simultaneously, while also delivering GLP-1 RAs. Unfortunately, Symlin (Pramlintide; AstraZeneca), the only commercial amylin analogue formulation, is formulated at pH~4 while Novolog (Aspart; Novonordisk) and Humalog (Lispro; Eli Lilly), insulin analogue formulations, are typically formulated at pH~7.4, meaning that these formulations are incompatible and must be administered in separate injections. While treatment of diabetes with separate injections of insulin and amylin analogues at mealtimes has been shown to be much more effective than insulin alone at managing diabetes, the administration of two separate injections is burdensome. We have developed a novel polymeric excipient that results in stable, ultra-fast acting insulin, to formulate insulin and pramlintide together to enable a single administration treatment mimicking endogenous hormone secretion. Additionally, we can ef...