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Is SUSTAIN-6 a fair comparison of semaglutide against its comparator arm?

Asked 1 Feb 2026Modified 2 months agoViewed 4.6k times
4

Numbers first: SUSTAIN-6 · semaglutide.

I am asking for verification rather than opinion, ideally with something I can read myself.

It is possible the evidence exists and I am searching for the wrong term.

Is this actually true, and what is the evidence?

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askedDr_Ravi_Selvarajah35k1371 Feb 2026

3 Answers

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24

Fair depends on the comparator arm, and in SUSTAIN-6 that means asking whether the comparator was titrated to the same ambition as the experimental one. A head-to-head that runs its comparator to a dose below the one it is licensed at is not measuring the two agents, it is measuring one agent against a handicapped version of the other. Check three things: the maximum comparator dose reached, the proportion of the comparator arm that reached it, and whether the titration schedules had the same duration. If those match, the comparison is fair on dosing and the argument moves to the endpoint. If they do not, the effect size is partly an artefact of the protocol.

A trial establishes what happened to a defined group under a defined protocol. Extending it beyond that group is inference, and inference is allowed as long as it is labelled.

Trial populations are selected. Exclusion criteria in this class routinely remove people with significant renal impairment, prior pancreatitis and unstable psychiatric illness, which is exactly the population the results are then quoted for.

Non-inferiority and superiority designs are not interchangeable. A non-inferiority result says the new agent is not meaningfully worse against a pre-specified margin — it does not say it is as good, and it certainly does not say it is better.

The cardiovascular outcome programme in this class runs to several large randomised trials — LEADER for liraglutide, SUSTAIN-6 and SELECT for semaglutide, REWIND for dulaglutide — and they are the reason the class is discussed as more than a weight intervention.

Read the protocol and the statistical analysis plan if the result matters to you. Both are usually published alongside.

edited 2 Jun 2026 by Dr_Ilse_Vandenberg — tightened the wording; no substantive change

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answeredDr_Ilse_Vandenberg113k24814 May 2026
2The number needed to treat is the framing that finally made this concrete for me. – marcus_thorbjorn 7 days ago
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16

The short version: the effect is real, the magnitude depends on the population, and the population is usually the part that gets dropped when a result is quoted second-hand.

Intention-to-treat and per-protocol analyses answer different questions. ITT asks what happens if you offer the treatment; per-protocol asks what happens if it is taken as directed. The gap between the two is a measure of how tolerable the protocol was.

Duration decides what can be seen. A 68-week trial can measure weight and glycaemia; it cannot measure anything whose event rate is one per cent per year without enrolling tens of thousands.

Registry entries at ClinicalTrials.gov carry the pre-specified primary endpoint with a timestamp, which is the cheapest available check on whether an endpoint was changed after the data were seen.

The caveat is that trial evidence is about licensed product administered under supervision. None of it transfers automatically to research-grade material of unverified content.

The short version: check the endpoint, check the comparator, check who was excluded, then look at the number.

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GA
answeredgrainne_ahearn50k383 May 2026
5Worth flagging that this changed with the 2025 publication, so older answers are out of date. – tabular_nums 9 months ago
6The exclusion criteria are the most informative page in the supplement and nobody reads them. – laminar_bench 18 days ago
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13

Answer first: read the primary endpoint, the comparator and the population before you read the effect size. Almost every argument on this site about a trial is really an argument about one of those three.

Confidence intervals matter more than point estimates when two trials disagree. Two studies reporting fifteen and twenty per cent whose intervals overlap heavily have not disagreed about anything.

The relevant detail is that a composite endpoint is only as informative as its least serious component. Where a cardiovascular composite combines death, infarction and stroke, ask which component moved, because they are not interchangeable outcomes.

Where a result is quoted from a conference abstract rather than a peer-reviewed publication, the numbers routinely move between the two. It is worth checking which one you are reading.

If a claim cannot be traced to a named trial with a named endpoint, treat it as a claim rather than as evidence.

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answeredtare_weight60k1486 Feb 2026

Your answer

Ask PeptideStack is a static archive. Posting is closed, but the norms are worth stating: answer the question that was asked, show your working, cite the trial or the certificate, and say plainly where the evidence runs out.

Not medical advice. Research-use-only compounds are not approved for human use.