Insulin Detemir (Levemir)

Insulin detemir was the first engineered insulin to reach the reversible-albumin-binding trick this site's insulin icodec and somapacitan pages describe in more extreme form — a real, twice-approved-a-decade-apart FDA case study, and the only basal insulin analog ever to earn an FDA pregnancy category B classification. Despite that record, Novo Nordisk discontinued it in the US entirely through 2024, a decision three US senators publicly questioned.

A first-generation version of the albumin-binding trick

Insulin detemir (Levemir, Novo Nordisk) reaches a longer-than-native duration of action through the same broad chemistry family this site's insulin icodec and somapacitan pages describe, just an earlier and less extreme version of it. The insulin molecule's terminal B-chain amino acid (threonine at position B30) is removed, and a 14-carbon myristic acid fatty chain is attached to the newly exposed LysB29 residue. That fatty tail lets the modified insulin bind reversibly to circulating albumin — roughly 98-99% of detemir in plasma is albumin-bound at any moment — creating a slow-release buffer that only lets small amounts of active, unbound insulin reach tissue at a time.³ The effect is real but far more modest than icodec's week-long profile or degludec's multi-hexamer depot: detemir's human half-life runs several hours longer than regular insulin's, giving a duration of action of roughly 12 to 24 hours depending on dose — enough for once- or twice-daily dosing, not the once-weekly interval later engineering tricks reached. It's a useful data point for exactly that reason: detemir shows what the albumin-binding idea alone gets you, before later insulins added heavier fatty-diacid tails and additional amino acid substitutions on top of it.

STEADINESS and the head-to-head trials against NPH and glargine

Detemir's FDA approval rested on a genuine multi-trial development program rather than a single pivotal study. In type 1 diabetes, the STEADINESS trial (Home PD, Bartley P, Russell-Jones D, et al., for the STEADINESS Study Group, "Insulin detemir offers improved glycemic control compared with NPH insulin in people with type 1 diabetes: a randomized clinical trial," Diabetes Care 2004;27(5):1081-1087, PMID 15111525) randomized 408 patients to twice-daily detemir or NPH insulin as basal therapy alongside mealtime insulin over 16 weeks open-label weeks; detemir produced significantly lower fasting plasma glucose and, pooled across its dosing arms, a lower HbA1c than NPH, alongside a 53% reduction in nocturnal hypoglycemia in one dosing arm. In type 2 diabetes, a separate 52-week, randomized, open-label, treat-to-target trial head-to-head against insulin glargine (Rosenstock J, Davies M, Home PD, Larsen J, Koenen C, Schernthaner G, "A randomised, 52-week, treat-to-target trial comparing insulin detemir with insulin glargine when administered as add-on to glucose-lowering drugs in insulin-naive people with type 2 diabetes," Diabetologia 2008;51(3):408-416, PMID 18204830) randomized 582 insulin-naive adults 1:1 to once-daily detemir or glargine, both actively titrated to a fasting glucose target of 6.0 mmol/L or below; the two insulins produced clinically similar HbA1c and hypoglycemia outcomes, with detemir showing slightly less weight gain and slightly more injection-site reactions — a genuinely close, non-inferiority-flavored result rather than a clear win for either analog.¹²

The FDA approved Levemir on 16 June 2005 (NDA 021536) for adults and adolescents with type 1 or type 2 diabetes. A supplemental approval on 22 May 2012, based on a 82-patient equivalence study against NPH, extended the label down to children as young as age 2 with type 1 diabetes — at the time, the first and only basal insulin analog cleared for that young an age group.

The only basal insulin ever granted FDA pregnancy category B

Why Novo Nordisk discontinued it in the US

Novo Nordisk announced on 8 November 2023 that it would discontinue Levemir in the US entirely, walking back a promise it had made only months earlier: on 14 March 2023, the company had announced it would cut Levemir's US list price by 65% effective 1 January 2024, as part of the broader round of insulin price cuts that also touched Novo Nordisk's other insulins. Instead of that price cut taking effect, Novo Nordisk discontinued the FlexPen device on 1 April 2024 and the vial formulation on 31 December 2024, citing "global manufacturing constraints, formulary losses impacting patient access, and the availability of alternative treatment options." US Senators Elizabeth Warren, Jeanne Shaheen, and Raphael Warnock sent Novo Nordisk a formal letter dated 17 April 2024 questioning that rationale, noting the company had recently announced an $11 billion purchase of three manufacturing facilities from Catalent and asking why manufacturing capacity was cited as a constraint at the same time. Novo Nordisk's public responses maintained the stated reasoning; the discontinuation went ahead on the announced schedule regardless.

Current status

Levemir is no longer available in the US in any form as of 31 December 2024. Patients and prescribers were directed toward NPH insulin, insulin glargine, or insulin degludec as substitutes, with particular attention paid to pregnant patients with diabetes, since detemir's pregnancy category B status and its supporting trial had made it a commonly preferred basal insulin during pregnancy specifically. Insulin detemir remains an approved, marketed medicine in the EU, UK, Canada and a number of other countries as of this review — the discontinuation was a US-market business decision by Novo Nordisk, not a global regulatory withdrawal or a safety-driven action anywhere.