Insulin detemir

In plain language

Insulin detemir is a long-acting insulin sold as Levemir that lasts up to about 24 hours. It works differently from glargine: it carries a small fatty acid tag.

That fatty acid makes the insulin stick to albumin, a common blood protein, both under the skin and in the bloodstream. Only a small fraction floats free and active at any time, which stretches out its effect and makes its action more predictable from person to person. Novo Nordisk stopped selling Levemir in the U.S. at the end of 2024.

For students

Insulin detemir acylates lysine B29 with a 14-carbon fatty acid (myristic acid; about 5,908 Da as the protein component) and omits threonine at B30. Albumin binding in tissue and plasma creates a slow-release reservoir, giving a duration of up to 24 hours at twice-daily dosing.

Its signature property is low between-patient variability in exposure and effect, the lowest among basal insulins in head-to-head studies, which matters clinically in patients prone to hypoglycemia. Novo Nordisk discontinued Levemir in the U.S. at the end of 2024, shifting manufacturing capacity to newer products; the molecule itself remains a licensed medicine elsewhere where marketed.

For researchers and instructors

Biochemistry. Albumin has multiple fatty-acid binding sites with fast on/off kinetics; the equilibrium between bound and free drug smooths concentration profiles rather than creating a depot in the classic sense.

Pharmacology. Dose-dependent duration (up to ~24 h), low intra- and inter-patient variability, and a weight-neutral or modestly weight-sparing effect versus NPH and glargine in some trials.

Human evidence. Pivotal trials showed non-inferiority to NPH and glargine with less nocturnal hypoglycemia; variability analyses are a standard citation in basal insulin literature.

Teaching point. First insulin to use reversible albumin binding as a half-life extension strategy, a concept later reused in other peptide classes.