Insulin (Regular), also known as Human Insulin, Humulin R, or Novolin R, is a synthetic form of insulin produced using recombinant DNA technology. It is typically synthesized in Escherichia coli, where chemically synthesized genes for the insulin A and B chains are expressed. This synthetic insulin is classified as a peptide hormone and is crucial for regulating glucose metabolism in the body. Researchers have focused on its production and purification processes to ensure its efficacy and safety for therapeutic use. The primary physiological role of insulin is to facilitate the uptake of glucose into cells, thus lowering blood glucose levels. It is a critical hormone in the management of diabetes, particularly in patients with type 1 diabetes who lack endogenous insulin production. Research has also explored its use in managing gestational diabetes and in patients requiring insulin during stress or surgery. Insulin acts by binding to the insulin receptor, a transmembrane receptor that triggers a cascade of intracellular events, including the activation of the PI3K/Akt pathway. This leads to increased glucose uptake by cells, particularly in muscle and adipose tissue, and promotes glycogen synthesis in the liver. Pharmacokinetically, regular insulin has a relatively short half-life and is typically administered via subcutaneous injection. It has a rapid onset of action, with effects beginning within 30 minutes and peaking at 2-3 hours. The duration of action is approximately 5-8 hours. Clinically, regular insulin is widely used for the management of diabetes mellitus and is approved by regulatory agencies such as the FDA. It is available by prescription and is considered a safe and effective treatment when used according to guidelines.