Objective: To review the pharmacology, pharmacokinetics, dosing guidelines, adverse effects, drug interactions, and clinical efficacy of insulin glargine.
Data sources: Primary and review articles regarding insulin glargine were identified by MEDLINE search (1966-July 2001); abstracts were identified through Institute for Scientific Information Web of Science (1995-July 2001) and the American Diabetes Association. Additional information was obtained from the insulin glargine product information.
Study selection and data extraction: All of the articles and meeting abstracts identified from the data sources were evaluated, and all information deemed relevant was included in this review. Priority was placed on data from the primary medical literature.
Data synthesis: Insulin glargine is a long-acting, recombinant human insulin analog that is given once daily as a basal source of insulin in patients with type 1 or type 2 diabetes mellitus. Modification of the basic insulin structure has produced a new insulin that is soluble at an acidic pH, but precipitates in the subcutaneous tissue and is slowly released from a depot. Insulin glargine has a slower onset of action than NPH insulin and a longer duration of action with no peak activity. Once-daily administration of insulin glargine has comparable efficacy to that of NPH insulin administered once or twice daily in basal-bolus regimens when used in combination with intermittent doses of regular insulin or insulin lispro in patients with type 1 and type 2 diabetes, and in conjunction with oral antidiabetic agents in patients with type 2 diabetes. Overall, insulin glargine has an incidence of hypoglycemia comparable to or less than that of NPH insulin, with a reduced incidence of nocturnal hypoglycemia compared with NPH insulin seen in some studies.
Conclusions: Insulin glargine is a long-acting insulin analog capable of providing 24-hour basal insulin coverage when administered once daily at bedtime. Its activity profile, which lacks a pronounced peak, more closely resembles that of endogenous basal insulin than that of other intermediate- or long-acting insulins and appears more likely to be associated with a reduced incidence of hypoglycemia, particularly nocturnal hypoglycemia. Insulin glargine physiologically provides basal insulin but, for most patients, the addition of a rapid-acting insulin, like insulin lispro, before or with meals will need to be included in the treatment regimen to achieve optimal management of blood glucose concentrations.