Liraglutide
NN2211, acylated GLP-1 analogue, Saxenda, Victoza
Liraglutide was the first acylated GLP-1 receptor agonist to reach wide clinical use and remains the reference point against which the weekly agents are judged. It is taken daily rather than weekly and produces less weight loss than semaglutide or tirzepatide, but it has a long and well-characterised outcome evidence base, including a cardiovascular outcome trial.
Mechanism
Liraglutide is a GLP-1 analogue that shares 97% sequence identity with native human GLP-1. Like all agents in this class it binds the GLP-1 receptor, a class B G-protein-coupled receptor, and signals through Gs-adenylate cyclase-cAMP-protein kinase A. In the pancreatic beta cell this amplifies glucose-stimulated insulin secretion in a glucose-dependent fashion; in the alpha cell it suppresses glucagon; in the stomach it slows gastric emptying; and in the arcuate nucleus of the hypothalamus and the hindbrain it reduces food intake and increases satiety.
Its pharmacokinetic engineering is simpler and less aggressive than semaglutide's. Two changes are made to native GLP-1: lysine 34 is replaced with arginine, and a palmitic acid chain is attached through a gamma-glutamyl spacer to lysine 26. The fatty acid promotes self-association into heptamers at the injection site, slowing absorption, and drives reversible albumin binding, which protects against renal clearance and dipeptidyl peptidase-4 degradation. The result is a half-life of about 13 hours rather than the two minutes of native GLP-1, but well short of semaglutide's week. That is a direct consequence of using a shorter, non-diacid fatty chain and of leaving the DPP-4-susceptible alanine at position 8 intact. The shorter half-life is the whole reason liraglutide is dosed daily and, in comparative trials, achieves less weight loss.
What the research shows
Liraglutide's evidence base is mature and hard-endpoint driven. LEADER randomised 9,341 people with type 2 diabetes at high cardiovascular risk and found cardiovascular death, non-fatal myocardial infarction or non-fatal stroke in 13.0% on liraglutide versus 14.9% on placebo over a median 3.8 years, with a significant reduction in cardiovascular death. This was one of the first demonstrations that a glucose-lowering drug could reduce cardiovascular mortality rather than merely not increase it.
For weight, the SCALE Obesity and Prediabetes trial randomised 3,731 adults without diabetes and reported a mean weight change of -8.4 kg on liraglutide 3.0 mg daily versus -2.8 kg on placebo at 56 weeks, with 63.2% versus 27.1% losing at least 5% of body weight. SCALE Diabetes, in 846 adults, showed a smaller effect in people with type 2 diabetes, around -6.0% versus -2.0%, reflecting the consistent observation across this whole drug class that weight loss is attenuated in the presence of diabetes. Head-to-head data place liraglutide clearly behind the weekly agents: semaglutide 2.4 mg produced roughly double the weight loss of liraglutide 3.0 mg in direct comparison. Liraglutide has also been studied in adolescents and in children aged 6 to 11 with obesity. Its main remaining clinical arguments are its shorter half-life, which allows faster withdrawal if problems arise, and the availability of generic versions since 2024.
Evidence assessment
High-quality evidence
A completed and published cardiovascular outcome trial in over 9,000 people plus multiple large randomised placebo-controlled weight-management trials, all three citations independently verified against PubMed and their registry records, supported by more than a decade of approved regulatory labelling in the US, UK and EU.
Tiers are applied consistently across the library and re-checked when new trials read out. Read the grading method.
Key studies
Liraglutide and Cardiovascular Outcomes in Type 2 Diabetes High-quality evidence
The composite of cardiovascular death, non-fatal myocardial infarction or non-fatal stroke occurred in 13.0% on liraglutide versus 14.9% on placebo, with a significant reduction in cardiovascular death.
A Randomized, Controlled Trial of 3.0 mg of Liraglutide in Weight Management High-quality evidence
Mean weight change was -8.4 kg with liraglutide 3.0 mg versus -2.8 kg with placebo, with 63.2% versus 27.1% losing at least 5% of body weight.
Efficacy of Liraglutide for Weight Loss Among Patients With Type 2 Diabetes: The SCALE Diabetes Randomized Clinical Trial High-quality evidence
Liraglutide 3.0 mg produced a mean weight loss of approximately 6.0% versus 2.0% with placebo in adults with type 2 diabetes, a smaller effect than seen in people without diabetes.
Safety
The adverse effect profile is the class profile. Gastrointestinal symptoms predominate: nausea, vomiting, diarrhoea and constipation, dose-related and generally worst in the first weeks. Because dosing is daily, these effects tend to be reported as less intense per episode but more frequent than with weekly agents. Labelled warnings include acute pancreatitis, gallbladder disease including cholelithiasis and cholecystitis (notably increased in the SCALE weight-management trials, where rapid weight loss itself is a contributor), acute kidney injury secondary to dehydration, and hypersensitivity reactions. Hypoglycaemia is uncommon with liraglutide alone but becomes a material risk in combination with insulin or sulfonylureas. Heart rate increases by a few beats per minute. Rodent studies showed thyroid C-cell hyperplasia and medullary thyroid tumours, producing the same contraindication in personal or family history of medullary thyroid carcinoma or MEN2 that applies across the class; the human relevance remains unproven. In LEADER, more gallbladder events and slightly more pancreatitis were seen on liraglutide. Because liraglutide has now been in wide clinical use since 2010, its postmarketing safety record is considerably longer and better characterised than that of any other peptide in this class.
Regulatory status
| Jurisdiction | Status |
|---|---|
| United Kingdom | Licensed by the MHRA for type 2 diabetes and, at 3.0 mg daily, for weight management alongside a reduced-calorie diet and increased physical activity. Prescription-only. NICE technology appraisal guidance covers NHS-funded use for weight management within specialist services. Generic versions are available. |
| United States | FDA approved for type 2 diabetes (2010) and, at the 3.0 mg daily dose, for chronic weight management (2014), with paediatric extensions covering adolescents and, for the diabetes indication, children aged 10 and above. Generic liraglutide entered the US market from 2024. Prescription-only. |
| WADA (sport) | Not prohibited. GLP-1 receptor agonists are not named on the WADA Prohibited List in or out of competition. |
Questions
Three practical reasons. Its 13-hour half-life means effects wash out within a day or two, which matters if tolerability is poor or surgery is planned. It has the longest postmarketing safety record in the class, dating to 2010. And generic versions have been available since 2024, which changes availability considerably. Against that, head-to-head data show it produces roughly half the weight loss of semaglutide 2.4 mg.
This is a consistent finding across the entire GLP-1 class, not specific to liraglutide: SCALE Diabetes showed about 6% weight loss against roughly 8% in people without diabetes in SCALE Obesity. Those were separate trials, so the comparison is indicative rather than a controlled contrast. Proposed explanations include concurrent weight-promoting diabetes medications, altered beta-cell and incretin responsiveness, and differences in baseline adiposity biology. It has not been definitively resolved.
It has the most extensive real-world exposure of any agent in this class, with LEADER providing nearly four years of randomised follow-up in over 9,000 people and more than a decade of postmarketing surveillance. That is a genuinely reassuring foundation. Recognised risks remain, chiefly pancreatitis, gallbladder disease and the unresolved rodent thyroid C-cell signal, and these appear in approved labelling.
A prespecified secondary analysis of LEADER found fewer new or worsening nephropathy events on liraglutide, driven mainly by reduced new-onset persistent macroalbuminuria. That is a secondary endpoint from a cardiovascular trial, not a dedicated kidney outcome trial, so it is weaker evidence than the FLOW trial provides for semaglutide. It is supportive rather than definitive.