Semaglutide

01 · What it is

Semaglutide has the strongest evidence base of any compound covered in this project, and that fact carries a specific implication rather than a general endorsement.

The evidence consists of cardiovascular outcome trials enrolling tens of thousands of participants, with hard endpoints and independent adjudication. SELECT randomised 8,803 participants to semaglutide and 8,801 to placebo — people with overweight or obesity and established cardiovascular disease, without diabetes — and reported a 20% reduction in major adverse cardiovascular events ^7,10. SOUL randomised 9,650 participants with type 2 diabetes and established atherosclerotic cardiovascular disease or chronic kidney disease ^6,18. FLOW examined chronic kidney disease outcomes in type 2 diabetes and reported that all confirmatory secondary outcomes favoured semaglutide, with the mean annual eGFR slope less steep by 1.16 mL per minute per 1.73 m² ¹¹.

What it is. Semaglutide is a glucagon-like peptide-1 receptor agonist with an extended half-life of approximately one week ¹. It exists in once-weekly subcutaneous and once-daily oral formulations, each with its own trial programme ^5,18.

Why the strength of the evidence is the point. Every result above was generated in a randomised, controlled, monitored setting, with a characterised product, at defined doses, in defined populations, with adverse events collected systematically. Those conditions are what make the numbers meaningful. None of that transfers to material obtained outside a regulated supply chain, where the product is uncharacterised, the setting unmonitored and the population unselected.

The literature also does not stop at benefit. A dedicated safety review notes that potential safety concerns have arisen over the years and that these were addressed within the phase 3 registration programme ⁴, and real-world evidence on utilisation and adverse effects of GLP-1 receptor agonist weight-loss therapies is now its own field ¹⁷.

02 · Evidence at a glance

Evidence grade

Approved Pharma — extensive randomised outcome-trial evidence

What it is

A GLP-1 receptor agonist with a half-life of approximately one week ¹

Formulations studied

Once-weekly subcutaneous ⁵; once-daily oral ^2,18

SELECT

8,803 on semaglutide vs 8,801 on placebo; 20% reduction in major adverse cardiovascular events in overweight/obesity with established cardiovascular disease, without diabetes ^7,10

SOUL

9,650 participants with type 2 diabetes and established atherosclerotic cardiovascular disease and/or chronic kidney disease ^6,18

SUSTAIN-6

Cardiovascular outcomes in type 2 diabetes at high cardiovascular risk ¹

PIONEER 6

Event-driven, randomised, double-blind, placebo-controlled trial of once-daily oral semaglutide at high cardiovascular risk ²

FLOW

Chronic kidney disease in type 2 diabetes; all confirmatory secondary outcomes favoured semaglutide; annual eGFR slope less steep by 1.16 mL/min/1.73 m² ¹¹

STEP 5

Two-year trial of once-weekly subcutaneous semaglutide 2.4 mg versus placebo, both with behavioural intervention ⁵

Heart failure

STEP-HFpEF and STEP-HFpEF DM pooled analysis ⁹; SELECT prespecified heart-failure analysis ¹²; four-trial pooled analysis ¹⁵

Prediabetes

STEP 10, randomised, double-blind, placebo-controlled phase 3 ¹⁴

Safety literature

A dedicated safety review ⁴; real-world adverse-effect evidence ¹⁷

Comparative data

Semaglutide versus tirzepatide, observational ¹³; cost-effectiveness modelling ¹⁶

Regulatory status

Prescription-only medicine

03 · Mechanism of action

A receptor agonist with an engineered half-life

Semaglutide is a glucagon-like peptide-1 analogue with an extended half-life of approximately one week ¹. GLP-1 is an incretin hormone; receptor agonism at pharmacological exposures affects glycaemic control and energy intake, which is the basis for both the diabetes and the weight-management indications.

The engineering achievement here is duration. Native GLP-1 is cleared within minutes, and the modifications that extend exposure to a week are what made once-weekly dosing possible.

Where the effects have been measured

The trial programme has looked well beyond glycaemia and body weight: cardiovascular events ^1,2,7,18, kidney outcomes ^10,11, heart failure with preserved ejection fraction ^9,12,15, and progression from prediabetes ¹⁴.

The breadth here is different in kind from the breadth this project has criticised elsewhere. In other guides, wide indication lists reflect a mechanism loose enough to show something anywhere. Here each indication was tested in its own adequately powered randomised trial with prespecified endpoints, and some of those trials were designed to detect harm as much as benefit.

The oral formulation is a separate pharmacological problem

Oral semaglutide required its own cardiovascular outcome programme — PIONEER 6 for safety ², then SOUL for efficacy, the latter noting explicitly that cardiovascular safety of the oral formulation had been established and that an assessment of cardiovascular efficacy was what SOUL set out to provide ¹⁸.

Peptides are not normally orally bioavailable. That an oral version exists at all, and that it needed its own outcome trials rather than inheriting the subcutaneous data, is a useful illustration of how seriously formulation changes are treated in regulated development.

04 · Key research findings

SUSTAIN-6, 2016. Cardiovascular outcomes in patients with type 2 diabetes at high cardiovascular risk, in a trial whose stated premise was that the cardiovascular effects of semaglutide were then unknown ¹.

The SUSTAIN programme, 2019. A review detailing efficacy and safety across SUSTAIN 1–5 and 7, and the cardiovascular safety profile from SUSTAIN 6 ³.

PIONEER 6, 2019. An event-driven, randomised, double-blind, placebo-controlled trial of once-daily oral semaglutide in patients at high cardiovascular risk ².

Safety review, 2021. A review addressing safety concerns raised over the years and how they were handled within the phase 3 registration trials including cardiovascular outcome trials ⁴.

Included deliberately. A guide that reports only the outcome trials would be reporting half of what the literature contains.

STEP 5, 2022. A two-year trial of once-weekly subcutaneous semaglutide 2.4 mg versus placebo, both alongside behavioural intervention, in adults with obesity or overweight with at least one weight-related comorbidity, without diabetes ⁵.

Two years is long by the standards of weight-management trials, and the design point worth noting is that both arms received behavioural intervention — the comparison is drug-plus-programme against programme alone.

SELECT, 2023. Semaglutide and cardiovascular outcomes in obesity without diabetes, addressing whether the drug could reduce cardiovascular risk associated with overweight and obesity in people without diabetes ⁷. The subsequent kidney-outcomes analysis records the headline result: a 20% reduction in major adverse cardiovascular events, with 8,803 participants on semaglutide and 8,801 on placebo ¹⁰.

This is the trial that changed how the drug is understood. It tested a cardiovascular endpoint in a population defined by weight rather than diabetes, and it is the single most consequential result in this guide.

FLOW, 2024. Effects on chronic kidney disease in patients with type 2 diabetes. All confirmatory secondary outcomes favoured semaglutide; the mean annual eGFR slope was less steep by 1.16 mL per minute per 1.73 m², with the risk of major cardiovascular events also reported ¹¹.

Heart failure analyses, 2024. A pooled analysis of STEP-HFpEF and STEP-HFpEF DM, in which semaglutide improved symptoms, physical limitations, bodyweight and exercise function in people with obesity-related heart failure with preserved ejection fraction ⁹; a prespecified analysis of SELECT in patients with prevalent heart failure ¹²; and a post-hoc participant-level pooled analysis across SELECT, FLOW, STEP-HFpEF and STEP-HFpEF DM ¹⁵.

The last of these is explicitly post-hoc and pooled, which the authors state. Post-hoc pooled analyses generate hypotheses; they do not carry the weight of the prespecified trials they draw on, and this guide reports them as what they are.

STEP 10, 2024. A randomised, double-blind, placebo-controlled multicentre phase 3 trial in people with obesity and prediabetes, addressing what the authors describe as limited existing data in that population ¹⁴.

Meta-analysis, 2024. An updated systematic review and meta-analysis of semaglutide 2.4 mg for weight in overweight or obese adults without diabetes, incorporating the two-year STEP 5 data ⁸.

Comparative and health-economic work, 2024–2025. An observational comparison of semaglutide and tirzepatide using propensity-score matching, in formulations labelled for type 2 diabetes and used on or off label ¹³; and lifetime health-effect and cost-effectiveness modelling of tirzepatide and semaglutide against other options and against lifestyle modification alone ¹⁶.

The comparative study is observational and explicitly includes off-label use. Propensity matching reduces confounding; it does not eliminate it, and this is not a randomised head-to-head comparison.

SOUL, 2025. Oral semaglutide and cardiovascular outcomes in high-risk type 2 diabetes, in 9,650 randomised participants, with prespecified analyses examining outcomes according to SGLT2 inhibitor use ^18,19. The trial’s design and baseline characteristics were published separately, three years before the result ⁶.

A design paper published in advance is a small thing to notice and a large thing to have. It fixes the endpoints, the population and the analysis plan in the public record before the data exist, which is the mechanism that makes a positive result mean what it appears to mean.

Real-world evidence, 2025. A narrative review of contemporary real-world evidence on utilisation, clinical and comparative effectiveness, and adverse effects of approved GLP-1 receptor agonist weight-loss therapies — liraglutide, semaglutide and tirzepatide ¹⁷. And a review positioning semaglutide within cardiovascular-kidney-metabolic syndrome ²⁰.

05 · Evidence overview

06 · Safety profile

This section reports the existence and structure of the safety literature. It does not enumerate adverse effects, contraindications, warnings or monitoring requirements, which are matters for the product label and for prescribing clinicians. This guide has read abstracts rather than full trial safety reports.

What exists. Safety was assessed across the phase 3 registration programme including cardiovascular outcome trials, and a dedicated review addresses the safety concerns that arose during development ⁴. Cardiovascular safety was the primary question for both SUSTAIN-6 ¹ and PIONEER 6 ² before efficacy trials followed. Real-world evidence on adverse effects of GLP-1 receptor agonist weight-loss therapies has developed into its own literature ¹⁷.

The sequence matters and is worth spelling out: cardiovascular safety was established first, in dedicated trials, before cardiovascular benefit was claimed. That is what regulated development looks like, and it is the structural feature most absent from every unapproved compound in this project.

What is genuinely unknown, and specific to this project’s context. Everything about administration outside prescribed conditions. All the evidence above was generated with a characterised product at known dose in monitored participants with defined baseline health, exclusion criteria, and systematic adverse-event collection.

Three gaps deserve naming. Product identity — no published analysis located here examines the identity, purity, concentration or contamination status of any semaglutide-labelled material obtained outside a pharmacy supply chain, and nothing about the trial evidence speaks to such material. Population selection — trial participants met eligibility criteria and were excluded on identifiable risks; an unselected population is a different population, and the same drug does not necessarily behave the same way in it. Absence of monitoring — the trials detected and managed adverse events through scheduled clinical contact, which is part of how those safety profiles were produced rather than an incidental feature of them.

07 · US regulatory status

Current as of 7 September 2026. Semaglutide is a prescription-only medicine. It is approved and marketed in the United States and many other jurisdictions, in subcutaneous and oral formulations, for indications established through the trial programmes described above ^{1,2,5,7,11,18}.

This guide has not consulted the FDA or EMA approval records, product labels or review documents, and makes no statement about specific approved indications, dosing, contraindications or warnings. Those belong to the label and to a prescriber.

Semaglutide is not a controlled substance. It is, however, a prescription drug, and supplying or obtaining prescription drugs outside a lawful prescription is unlawful in the United States and in most other jurisdictions.

Under the World Anti-Doping Code, competitors should consult the current Prohibited List directly rather than rely on secondary summaries, including this one.

08 · Limitations of the evidence

1. The evidence attaches to a regulated product used under prescribed conditions. Every finding in this guide was generated with a characterised product, at a defined dose, in a selected and monitored population. Those conditions are part of the result, not a formality around it.
2. Trial populations are selected. SELECT enrolled people with established cardiovascular disease and without diabetes ⁷; SOUL enrolled people with type 2 diabetes and established atherosclerotic cardiovascular disease or chronic kidney disease ^6,18; STEP 5 enrolled adults with obesity or overweight with at least one weight-related comorbidity ⁵. Results do not automatically extend beyond the populations tested.
3. Some influential analyses are post-hoc or pooled. The four-trial heart failure analysis is explicitly described as post-hoc ¹⁵. Its authors say so; a reader should weight it accordingly.
4. The head-to-head comparison with tirzepatide is observational ¹³, propensity-matched, and includes off-label use. It is not a randomised comparison.
5. This guide reports no adverse-event data. Not because the literature lacks it — the literature has a great deal — but because abstracts are not the appropriate source for it and a product label is.
6. Trials of weight outcomes included behavioural intervention in both arms ⁵, so the effect measured is what the drug adds to a programme, not what it does alone.
7. Sponsor involvement runs through the trial literature, as is normal for a registration programme, with recurring investigator groups across trials ^{1,2,5,7,11,18}. Disclosure practice appears standard for the field.
8. Cost-effectiveness modelling depends on its assumptions ¹⁶ and is not clinical evidence.
9. Fewer than twenty-five of roughly 1,750 records were examined on this search, weighted toward outcome trials and safety literature.
10. This guide has read abstracts, not full texts, for every source cited.
11. Nothing is known about non-pharmacy material. No published analysis located here has examined any semaglutide-labelled product obtained outside a regulated supply chain.

09 · Legal and regulatory appendix

This appendix applies to every compound in this family and is reproduced in each guide.

Prescription status. Semaglutide is a prescription-only medicine wherever it is approved. Obtaining, supplying, possessing for supply, importing or administering prescription medicines outside a lawful prescription is unlawful in the United States and in most other jurisdictions. This guide does not describe how to obtain the compound and takes no position on any supplier.

Compounded and unapproved preparations. Preparations labelled as semaglutide that are not approved products have no established relationship to the material used in the trials cited here. This guide located no published analysis of the identity, purity, concentration, sterility or contamination status of any such preparation. Nothing in the trial evidence described above should be read as applying to them.

Research-use labelling. Material labelled for laboratory research use is not manufactured, tested, or released to the standards applied to medicines intended for people, and such labelling does not make administration lawful or safe.

What this guide is. A description of the published peer-reviewed literature, written for readers who want to understand the state of the evidence. It is not medical advice, not a recommendation, not an endorsement, and not a substitute for a clinician who can assess an individual situation.

Editorial position. Arkham Labs publishes independently and earns through disclosed referral links. That commercial relationship is disclosed on every page carrying such a link and on the editorial standards page. It does not alter what the evidence says, and this guide reports the evidence for a prescription medicine precisely as the literature states it, including where that evidence is strong.

10 · References

1. Marso SP, Bain SC, Consoli A, Eliaschewitz FG, Jódar E, Leiter LA, Lingvay I, Rosenstock J, Seufert J, Warren ML, Woo V, Hansen O, Holst AG, Pettersson J, Vilsbøll T; SUSTAIN-6 Investigators. Semaglutide and cardiovascular outcomes in patients with type 2 diabetes. N Engl J Med. 2016 Nov 10;375(19):1834–1844.

   PMID 27633186 ↗

2. Husain M, Birkenfeld AL, Donsmark M, Dungan K, Eliaschewitz FG, Franco DR, Jeppesen OK, Lingvay I, Mosenzon O, Pedersen SD, Tack CJ, Thomsen M, Vilsbøll T, Warren ML, Bain SC; PIONEER 6 Investigators. Oral semaglutide and cardiovascular outcomes in patients with type 2 diabetes. N Engl J Med. 2019 Aug 29;381(9):841–851.

   PMID 31185157 ↗

3. Aroda VR, Ahmann A, Cariou B, Chow F, Davies MJ, Jódar E, Mehta R, Woo V, Lingvay I. Comparative efficacy, safety, and cardiovascular outcomes with once-weekly subcutaneous semaglutide in the treatment of type 2 diabetes: insights from the SUSTAIN 1-7 trials. Diabetes Metab. 2019 Oct;45(5):409–418. Review.

   PMID 30615985 ↗

4. Smits MM, Van Raalte DH. Safety of semaglutide. Front Endocrinol (Lausanne). 2021 Jul 7;12:645563. Review.

   PMID 34305810 ↗

5. Garvey WT, Batterham RL, Bhatta M, Buscemi S, Christensen LN, Frias JP, Jódar E, Kandler K, Rigas G, Wadden TA, Wharton S; STEP 5 Study Group. Two-year effects of semaglutide in adults with overweight or obesity: the STEP 5 trial. Nat Med. 2022 Oct;28(10):2083–2091.

   PMID 36216945 ↗

6. McGuire DK, Busui RP, Deanfield J, Inzucchi SE, Mann JFE, Marx N, Mulvagh SL, Poulter N, Engelmann MDM, Hovingh GK, Ripa MS, Gislum M, Brown-Frandsen K, Buse JB. Effects of oral semaglutide on cardiovascular outcomes in individuals with type 2 diabetes and established atherosclerotic cardiovascular disease and/or chronic kidney disease: design and baseline characteristics of SOUL, a randomized trial. Diabetes Obes Metab. 2023 Jul;25(7):1932–1941.

   PMID 36945734 ↗

7. Lincoff AM, Brown-Frandsen K, Colhoun HM, Deanfield J, Emerson SS, Esbjerg S, Hardt-Lindberg S, Hovingh GK, Kahn SE, Kushner RF, Lingvay I, Oral TK, Michelsen MM, Plutzky J, Tornøe CW, Ryan DH; SELECT Trial Investigators. Semaglutide and cardiovascular outcomes in obesity without diabetes. N Engl J Med. 2023 Dec 14;389(24):2221–2232.

   PMID 37952131 ↗

8. Qin W, Yang J, Deng C, Ruan Q, Duan K. Efficacy and safety of semaglutide 2.4 mg for weight loss in overweight or obese adults without diabetes: an updated systematic review and meta-analysis including the 2-year STEP 5 trial. Diabetes Obes Metab. 2024 Mar;26(3):911–923.

   PMID 38016699 ↗

9. Butler J, Shah SJ, Petrie MC, Borlaug BA, Abildstrøm SZ, Davies MJ, Hovingh GK, Kitzman DW, Møller DV, Verma S, Einfeldt MN, Lindegaard ML, Rasmussen S, Kosiborod MN; STEP-HFpEF Trial Committees and Investigators. Semaglutide versus placebo in people with obesity-related heart failure with preserved ejection fraction: a pooled analysis of the STEP-HFpEF and STEP-HFpEF DM randomised trials. Lancet. 2024 Apr 27;403(10437):1635–1648.

   PMID 38599221 ↗

10. Colhoun HM, Lingvay I, Brown PM, Deanfield J, Brown-Frandsen K, Kahn SE, Plutzky J, Node K, Parkhomenko A, Rydén L, Wilding JPH, Mann JFE, Tuttle KR, Idorn T, Rathor N, Lincoff AM. Long-term kidney outcomes of semaglutide in obesity and cardiovascular disease in the SELECT trial. Nat Med. 2024 Jul;30(7):2058–2066.

    PMID 38796653 ↗

11. Perkovic V, Tuttle KR, Rossing P, Mahaffey KW, Mann JFE, Bakris G, Baeres FMM, Idorn T, Bosch-Traberg H, Lausvig NL, Pratley R; FLOW Trial Committees and Investigators. Effects of semaglutide on chronic kidney disease in patients with type 2 diabetes. N Engl J Med. 2024 Jul 11;391(2):109–121.

    PMID 38785209 ↗

12. Deanfield J, Verma S, Scirica BM, Kahn SE, Emerson SS, Ryan D, Lingvay I, Colhoun HM, Plutzky J, Kosiborod MN, Hovingh GK, Hardt-Lindberg S, Frenkel O, Weeke PE, Rasmussen S, Goudev A, Lang CC, Urina-Triana M, Pietilä M, Lincoff AM; SELECT Trial Investigators. Semaglutide and cardiovascular outcomes in patients with obesity and prevalent heart failure: a prespecified analysis of the SELECT trial. Lancet. 2024 Aug 24;404(10454):773–786.

    PMID 39181597 ↗

13. Rodriguez PJ, Goodwin Cartwright BM, Gratzl S, Brar R, Baker C, Gluckman TJ, Stucky NL. Semaglutide vs tirzepatide for weight loss in adults with overweight or obesity. JAMA Intern Med. 2024 Sep 1;184(9):1056–1064.

    PMID 38976257 ↗

14. McGowan BM, Bruun JM, Capehorn M, Pedersen SD, Pietiläinen KH, Muniraju HAK, Quiroga M, Varbo A, Lau DCW; STEP 10 Study Group. Efficacy and safety of once-weekly semaglutide 2.4 mg versus placebo in people with obesity and prediabetes (STEP 10): a randomised, double-blind, placebo-controlled, multicentre phase 3 trial. Lancet Diabetes Endocrinol. 2024 Sep;12(9):631–642.

    PMID 39089293 ↗

15. Kosiborod MN, Deanfield J, Pratley R, Borlaug BA, Butler J, Davies MJ, Emerson SS, Kahn SE, Kitzman DW, Lingvay I, Mahaffey KW, Petrie MC, Plutzky J, Rasmussen S, Rönnbäck C, Shah SJ, Verma S, Weeke PE, Lincoff AM; SELECT, FLOW, STEP-HFpEF, and STEP-HFpEF DM Trial Committees and Investigators. Semaglutide versus placebo in patients with heart failure and mildly reduced or preserved ejection fraction: a pooled analysis of the SELECT, FLOW, STEP-HFpEF, and STEP-HFpEF DM randomised trials. Lancet. 2024 Sep 7;404(10456):949–961.

    PMID 39222642 ↗

16. Hwang JH, Laiteerapong N, Huang ES, Kim DD. Lifetime health effects and cost-effectiveness of tirzepatide and semaglutide in US adults. JAMA Health Forum. 2025 Mar 7;6(3):e245586.

    PMID 40085108 ↗

17. Thomsen RW, Mailhac A, Løhde JB, Pottegård A. Real-world evidence on the utilization, clinical and comparative effectiveness, and adverse effects of newer GLP-1RA-based weight-loss therapies. Diabetes Obes Metab. 2025 Apr;27 Suppl 2:66–88. Review.

    PMID 40196933 ↗

18. McGuire DK, Marx N, Mulvagh SL, Deanfield JE, Inzucchi SE, Pop-Busui R, Mann JFE, Emerson SS, Poulter NR, Engelmann MDM, Ripa MS, Hovingh GK, Brown-Frandsen K, Bain SC, Cavender MA, Gislum M, David JP, Buse JB; SOUL Study Group. Oral semaglutide and cardiovascular outcomes in high-risk type 2 diabetes. N Engl J Med. 2025 May 29;392(20):2001–2012.

    PMID 40162642 ↗

19. Marx N, Deanfield JE, Mann JFE, Arechavaleta R, Bain SC, Bajaj HS, Bayer Tanggaard K, Birkenfeld AL, Buse JB, Davicevic-Elez Z, Desouza C, Emerson SS, Engelmann MDM, Hovingh GK, Inzucchi SE, Jhund PS, Mulvagh SL, Pop-Busui R, Poulter NR, Rasmussen S, Tu ST, McGuire DK; SOUL Study Group. Oral semaglutide and cardiovascular outcomes in people with type 2 diabetes, according to SGLT2i use: prespecified analyses of the SOUL randomized trial. Circulation. 2025 Jun 10;151(23):1639–1650.

    PMID 40156843 ↗

20. MacIsaac RJ. Semaglutide: a key medication for managing cardiovascular-kidney-metabolic syndrome. Future Cardiol. 2025 Jul;21(9):663–683. Review.

    PMID 40458885 ↗