Insulin lispro is a rapid-acting form of insulin used for the treatment of hyperglycemia caused by Type 1 and Type 2 Diabetes. Chemically, insulin lispro is Lys(B28), Pro(B29) human insulin analog, created when the amino acids at positions 28 and 29 on the insulin B-chain are reversed. Insulin lispro is synthesized in a special non-pathogenic laboratory strain of Escherichia coli bacteria that has been genetically altered by the addition of the gene for insulin lispro. Regulation of glucose metabolism is the primary activity of insulins and insulin analogs, including insulin lispro products. Insulins lower blood glucose by stimulating peripheral glucose uptake by skeletal muscle and fat, and by inhibiting hepatic glucose production. Insulins inhibit lipolysis and proteolysis, and enhance protein synthesis. Insulin lispro begins to exert its effects within 15 minutes of subcutaneous administration, while peak levels occur 30 to 90 minutes after administration. Due to its duration of action of around 5 hours, Humalog is considered "bolus insulin" as it provides high levels of insulin in a short period of time to mimic the release of endogenous insulin from the pancreas after meals. Bolus insulin is often combined with once daily, long-acting "basal insulin" to provide low concentrations of background insulin that can keep blood sugar stable between meals or overnight. Use of basal and bolus insulin together is intended to mimic the pancreas' production of endogenous insulin, with a goal of avoiding any periods of hypoglycemia.