Insulin and insulin analogs
/ Class page — recombinant human insulin and engineered analogs (rapid: lispro, aspart, glulisine; long: glargine, detemir, degludec; ultra-long: icodec)ALIAS · Insulin · Recombinant human insulin · Humulin · Novolog · Lantus · Levemir · Tresiba
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Tier 1. Class page covering recombinant human insulin and engineered analogs. Recombinant human insulin (Humulin, Novolin) entered clinical use in 1982; the rapid-acting analogs (lispro 1996, aspart 2000, glulisine 2004), long-acting basal analogs (glargine 2000, detemir 2005, degludec 2015), and ultra-long-acting once-weekly icodec (FDA approval 2024 deferred for further data; approved in EU and other jurisdictions) span four decades of structural engineering for pharmacokinetic optimisation.
Insulin is the 51-residue two-chain peptide hormone (A chain 21 residues, B chain 30 residues, three disulfide bonds) secreted by pancreatic beta cells in response to glucose, amino acids, and incretin signals. Receptor binding at the insulin receptor tyrosine kinase activates IRS-1/2, PI3K-Akt, and Ras-MAPK signalling cascades that drive glucose uptake into muscle and adipose tissue (via GLUT4 translocation), suppress hepatic glucose output, and regulate lipid and protein metabolism. Engineered analogs alter specific residues to modify self-association, isoelectric point, or albumin binding — producing faster onset (lispro: B28 Pro to Lys, B29 Lys to Pro, reducing dimerisation), prolonged action (glargine: A21 Asn to Gly plus B-chain diarginine extension, isoelectric precipitation at neutral pH; detemir: B29 acylation with myristic acid for albumin binding; degludec: B29 acylation with hexadecanedioic acid via gamma-glutamate spacer for multi-hexamer formation), or ultra-long once-weekly action (icodec: extensive acylation and structural modifications for albumin retention).
Tier 1. Recombinant human insulin and the major analogs are supported by hundreds of randomised trials across type 1 and type 2 diabetes. Hirsch (Lancet 2005 NEJM review) summarised the rapid- and long-acting analog era's pharmacology and clinical positioning. Russell-Jones (Lancet Diabetes Endocrinology 2012) reviewed comparative analog versus human insulin glycemic and hypoglycemia outcomes. The ONWARDS Phase 3 program (Rosenstock 2023 NEJM and other ONWARDS reports) established once-weekly insulin icodec non-inferiority for HbA1c reduction versus daily basal analogs in multiple type 2 diabetes populations. This class page does not summarise every individual analog's pivotal trials.
Hypoglycemia is the dose-limiting class adverse event; hypoglycemia risk varies by analog (long-acting analogs generally show lower nocturnal hypoglycemia than NPH). Weight gain is common with intensification. Injection-site reactions, lipohypertrophy at unrotated injection sites, and rare immunogenicity (more common with older animal-derived insulins, largely resolved with recombinant human insulin and analogs) are reported. Once-weekly icodec adds a class-specific consideration: the long elimination half-life amplifies the duration of any hypoglycemic excursion if dose-finding is imperfect.
Regulatory status
- FDA status:
- FDA-approved
- Compounding:
- Not eligible for compounding (approved, not in shortage)
Insulin analog pharmacology is well-characterised for individual molecules but the comparative-effectiveness literature has nuanced findings — meta-analyses generally show small absolute HbA1c differences between analogs and human insulin, with the principal analog advantages being hypoglycemia reduction (especially nocturnal) and dosing flexibility rather than glycemic control magnitude. US insulin pricing remains a substantial access concern that the underlying clinical evidence does not address. The 2024 FDA Complete Response Letter for icodec in type 1 diabetes (citing concerns about hypoglycemia in T1DM and the ONWARDS-6 imbalance) reflects analog-specific regulatory caution.