A prespecified secondary analysis of the SELECT trial found that once-weekly semaglutide 2.4 mg reduced the inflammatory biomarker hsCRP by 37.8% versus placebo at week 104. Reductions appeared within 4 weeks, before substantial weight loss, and among participants with minimal or no weight loss.…
Once-weekly semaglutide 2.4 mg reduced the inflammatory biomarker high-sensitivity C-reactive protein hsCRP by 37.8% versus placebo at week 104 in the SELECT trial, a prespecified secondary analysis published in Circulation finds. The paper, by Plutzky, J., et al., appears in volume 154 of the journal with the DOI 10.1161/CIRCULATIONAHA.125.074482. A medical science summary of the study for clinical readers, written by Pooja Toshniwal Paharia, an oral and maxillofacial physician and radiologist based in Pune, India, and reviewed by Susha Cheriyedath, M.Sc., was published on August 24, 2026.
The analysis directly examined whether changes in systemic inflammation contribute to the cardiovascular benefits semaglutide demonstrated in the main SELECT results, rather than assuming those benefits flow entirely from weight loss. SELECT, a Novo Nordisk-funded phase 3 trial, randomized 17,604 adults with established atherosclerotic cardiovascular disease ASCVD , overweight or obesity, and no diabetes to once-weekly subcutaneous semaglutide or placebo on top of standard medical therapy; 17,485 participants had baseline hsCRP measurements. The results showed that hsCRP reductions were rapid, that they appeared before substantial weight loss, that they occurred even in participants with minimal or no weight loss, and that accounting for hsCRP change only partially attenuated the drug's estimated cardiovascular benefit.
Each observation is consistent with the hypothesis that semaglutide, a GLP-1 receptor agonist peptide, exerts anti-inflammatory effects that contribute to its cardiovascular benefit. None of them, alone or together, proves that reduced inflammation is the mechanism, and the authors do not claim proof. They note that hsCRP is a single biomarker with no established role as a pathogenic mediator, that the findings do not confirm a weight-independent anti-inflammatory mechanism, and that changes in adipose tissue, diet, and GLP-1 receptor signaling are all candidate drivers. The study's contribution is to put the inflammatory hypothesis on a quantitative footing large enough to test and to define the limits of what a secondary biomarker analysis can establish.
The timing data come from 6,011 European participants who underwent additional laboratory testing at weeks 4 and 8. In that subgroup, hsCRP fell by 12% at 4 weeks and 19% at 8 weeks. By the time of these early measurements, the dose had been titrated to only 0.5 mg/week, far below the 2.4 mg maintenance dose, and average body weight loss was 1.4% at 4 weeks and 2.8% at 8 weeks. The primary biomarker analysis at week 104 showed a placebo-corrected reduction of 37.8% in geometric mean hsCRP.
The early response is the most instructive element of the study because of the context. Weight loss was still minimal at weeks 4 and 8, yet the biomarker was already moving. The authors also reported that hsCRP fell among participants with minimal or no weight loss and that greater weight loss was associated with larger reductions. Together these patterns indicate that weight loss amplifies the hsCRP response but is not a prerequisite for it.
That formulation requires a caution. The authors did not claim proof of a weight-independent anti-inflammatory mechanism. Even a 1.4% loss of body weight reflects negative energy balance, which lowers inflammatory tone on its own. GLP-1 receptor agonists also change food intake, hepatic fat, and adipose tissue biology within weeks of the first dose. The temporal data establish that the biomarker signal emerges earlier than a weight-centric model would predict. They do not establish what drives the signal.
Consistency across subgroups strengthens the finding. The reduction was seen across baseline LDL cholesterol tertiles, across all three cardiovascular entry criteria, and among the 88% of participants on baseline statin therapy. Women showed a larger proportional reduction than men, with estimated treatment ratios of 0.56 versus 0.65 P < 0.0001 . The authors reported the sex difference without identifying its mechanism.
SELECT was conducted at 804 sites in 41 countries with a mean follow-up of 39.8 months. Participants were at least 45 years old with prior myocardial infarction, stroke, or symptomatic peripheral artery disease, a body mass index of at least 27 kg/m², and no diabetes. Prior diabetes or an HbA1c of at least 6.5% excluded participants. Randomization was 1:1 to semaglutide or placebo. The endpoints examined in this analysis were change in hsCRP concentration, major adverse cardiovascular events MACE , cardiovascular death, all-cause mortality, and body weight change.
Baseline hsCRP was strongly prognostic. Compared with participants whose baseline hsCRP was below 2 mg/L, those with values of 10 mg/L or higher had a hazard ratio of 2.17 95% CI 1.81 to 2.58 for MACE, 3.94 95% CI 3.04 to 5.08 for cardiovascular death, and 3.40 95% CI 2.77 to 4.14 for all-cause mortality. These gradients emerged in a population where 88% were already taking statins, drugs that themselves lower hsCRP. Residual inflammatory risk is therefore quantifiable and clinically meaningful even on contemporary secondary prevention therapy.
The evidentiary limits deserve direct statement. Semaglutide assignment was randomized, so the estimate of the drug's effect on hsCRP supports a causal reading. But hsCRP change is a post-randomization variable, which makes the connection between biomarker change and clinical benefit a form of observational mediation analysis. Unmeasured confounding, the timing of blood sampling, and the correlation between weight change and hsCRP change all shape the result. The authors used time-dependent Cox models in which accounting for hsCRP changes only partially attenuated semaglutide's estimated cardiovascular benefit. That is the appropriate statistical evidence available in a trial of this design, and it supports partial mediation. It cannot assign a precise causal fraction to inflammation.
hsCRP is an acute-phase protein synthesized mainly in the liver in response to interleukin-6 and related inflammatory cytokines. It is a standardized, stable clinical measure of low-grade systemic inflammation, but it is not itself considered a pathogenic mediator of atherosclerosis. Its value in this analysis is as a readout of upstream inflammatory activity, not as a direct actor in plaque biology.
The upstream sources matter for interpretation. In obesity, visceral adipose tissue becomes inflamed, with macrophage infiltration and cytokine release that drive hepatic CRP synthesis. Weight loss reduces that drive, which is the classic explanation for falling hsCRP in weight-loss trials. The SELECT data do not overturn that explanation; they narrow it. The 4- and 8-week reductions, achieved at a dose of 0.5 mg/week with weight loss still under 3%, are consistent with a pharmacological effect that begins before significant fat loss, and remain compatible with adipose tissue changes that start early in caloric restriction.
Direct mechanisms are also biologically plausible. GLP-1 receptors are expressed on monocytes, macrophages, and lymphocytes. Preclinical work has shown that GLP-1 receptor agonists push macrophages toward anti-inflammatory phenotypes and reduce cytokine production. The authors explicitly listed changes in adipose tissue, diet, GLP-1 receptor signaling, and other biological processes as candidate contributors, and the trial cannot separate them.
The sex difference in the treatment ratio is a useful pointer for future work. Women reached an estimated treatment ratio of 0.56 versus 0.65 in men, a difference with P < 0.0001. Sex differences in body composition, fat distribution, and baseline inflammatory tone could explain it, but the analysis did not test those pathways. The finding is a lead for mechanistic studies, not a settled result.
The phrase "partially attenuated" is the hinge of the paper. In time-dependent Cox models, adding hsCRP change to the model reduced the estimated cardiovascular benefit of semaglutide but did not eliminate it. That is the statistical signature of a contributor that accounts for some, but not all, of the treatment effect.
The interpretation should be careful in two directions. Partial attenuation does not prove that inflammation mediates a fixed share of the benefit. Measurement error in hsCRP, the timing of sampling relative to events, and the strong correlation between weight loss and hsCRP change all tend to understate or obscure the true relationship. Conversely, partial attenuation does not prove that semaglutide's benefit is substantially weight-independent. The residual treatment effect in the model could reflect the parts of the weight-loss mechanism that do not run through hsCRP, or through any single biomarker.
What the analysis does establish is a coherent chain of observation: semaglutide lowers hsCRP rapidly and durably; baseline hsCRP strongly predicts events; and adjusting for the biomarker shift moves the treatment estimate. Each link is individually solid. The chain as a whole supports a mechanistic hypothesis that inflammation contributes to the cardiovascular benefit. The authors, notably, did not overstate it. The paper does not claim that hsCRP reduction directly causes the benefit, does not claim a weight-independent anti-inflammatory mechanism, and does not present hsCRP as a test for selecting patients who will respond to semaglutide.
That restraint matters for how the field consumes the result. The next step is not to treat hsCRP as a surrogate endpoint for semaglutide. It is to test the causal question with designs that can answer it: repeated biomarker measurement with formal mediation methods, mechanistic studies of immune cell phenotype and adipose tissue in humans, and, ultimately, trials that modify inflammation directly.
Semaglutide's registered-trial base is broad. Peptide Atlas files 668 registered clinical trials for semaglutide, with 10 currently recruiting. The phase breakdown on file lists 4 Phase 2 trials, 4 Phase 4 trials, and 1 Phase 3 trial. The recruiting trials show where the molecule is being tested next:
The indexed literature shows a similar expansion. Peptide Atlas lists 197 PubMed-indexed papers on semaglutide. Recent contributions include a systematic review and meta-analysis of long-term safety and renal outcomes in non-diabetic obesity with chronic kidney disease or hypertension PMID 42340790; Clin Ter, July 2026 , a systematic review of weight-lowering drugs and natural female fertility PMID 42307450; Clin Obes, July 2026 , a randomized trial of semaglutide and effort-based decision-making in major depressive disorder PMID 42054055; JAMA Psychiatry, July 2026 , the STRIDE trial of semaglutide in peripheral artery disease and diabetes PMID 41780559; Eur Heart J, July 2026 , and a…
Peptides referenced: Semaglutide, GLP-1.
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