CT-388 adds a second receptor that Wegovy does not have, and changes how both are activated. Wegovy has 14.9% weight loss over 68 weeks in 1,961 people; CT-388 has 8% over 29 days in a phase 1. One is a finished argument and the other is a proposal.
Side by side
| CT-388 | Wegovy | |
|---|---|---|
| Status | Investigational, phase 3 | FDA approved |
| Targets | GLP-1 and GIP, signalling-biased | GLP-1 only |
| Weight loss | up to 8.0% at day 29 | 14.9% at 68 weeks |
| Evidence | One phase 1 trial | Full phase 3 programme |
| Nausea | No figures published | 44% |
| Cardiovascular indication | No | Yes, approved |
| Can you get it | No | Yes |
| Maker | Roche | Novo Nordisk |
Two differences, not one
Most coverage treats CT-388 as "another dual agonist". It is making two separate departures from Wegovy.
The extra receptor. Wegovy activates GLP-1 alone. CT-388 adds GIP, which is the change tirzepatide already made and which produced roughly six more percentage points of weight loss. On that axis CT-388 is following a proven path.
The biased signalling. This is the untested part. CT-388 is engineered to activate both receptors while causing minimal internalisation — the process by which a stimulated receptor is pulled inside the cell and briefly taken out of service. The claim is that receptors left available keep responding. Nothing in the published data tests that over a meaningful period.
Why the numbers cannot be lined up
Day 29 against week 68. Not the same measurement at different scales — different measurements. CT-388 losing 8% in a month says the effect arrives quickly; it says nothing about the plateau, and every drug in this class has one.
The useful comparison is not available and will not be until Roche publishes a longer trial. Anyone stating that CT-388 beats or trails Wegovy is filling that gap with guesswork.
What Wegovy has that CT-388 cannot answer
A cardiovascular indication. Wegovy is approved to reduce major cardiovascular events in adults with cardiovascular disease and overweight or obesity, from a dedicated outcomes trial. CT-388 has no cardiovascular outcomes trial published and no such approval. For a reader with heart disease, that single row settles the page.
A safety profile you can read. Wegovy's label lists every reaction above 2% by dose: 44% nausea, 30% diarrhoea, 24% vomiting. CT-388's published safety data is one sentence saying most adverse events were mild or moderate. Not reassuring or alarming — simply absent.
And availability. Wegovy can be prescribed today. CT-388 is in phase 3 and recruiting; a trial is the only route.
Where CT-388 might land
If the biased-agonism premise holds, CT-388 would be competing with tirzepatide rather than semaglutide — two receptors against one puts it in a different bracket from Wegovy, and the comparison worth making is CT-388 vs Zepbound.
If it does not hold, it is another dual agonist arriving several years after the first one, into a market that will also contain triple agonists and amylin combinations. The whole field is in the GLP-1 pipeline tracker.
Scientific References
3 sources- 1
Chakravarthy MV, Rodriguez R, Hergarden A, et al.
Effects of CT-388, a once-weekly signaling-biased dual GLP-1/GIP receptor agonist, on weight loss and glycemic control in preclinical models and participants with obesity
Molecular Metabolism · 103 · 2026PMID: 41319798
NIH - 2
Novo Nordisk
WEGOVY (semaglutide) — Prescribing Information, §6.1 Table 3
DailyMed, U.S. National Library of Medicine · 2026
NIH - 3
Wilding JPH, Batterham RL, Calanna S, et al.
Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP-1)
New England Journal of Medicine · 384(11) · 2021PMID: 33567185
NEJM
References open in a new tab. Content is reviewed against peer-reviewed literature as part of our editorial policy.
About the author
Editor, Modern Weight Science
Claudiu Gheorghe is the editor of Modern Weight Science. He is not a physician. His role is to synthesize peer-reviewed studies, clinical-trial data, and FDA prescribing information into clear, plain-language explanations, and to make sure every factual claim on the site traces back to a cited source. Any decision about starting, changing, or stopping a medication belongs with a licensed clinician who knows your history.
Every claim is checked against peer-reviewed research through our review process and fact-checking policy.
Frequently Asked Questions
Is CT-388 better than Wegovy?
No evidence answers this. CT-388's published figure is up to 8% weight loss at day 29 from a phase 1 trial; Wegovy's 14.9% comes from 1,961 people over 68 weeks. A four-week result and a sixty-eight-week result are different measurements, not the same measurement at different scales.
How is CT-388 different from Wegovy?
In two ways. It adds the GIP receptor, which Wegovy does not target — the same change tirzepatide made, which produced about six more percentage points of weight loss. And it is engineered to activate both receptors while causing minimal internalisation, so they stay available. The second difference is the untested one.
Does CT-388 protect the heart like Wegovy?
Not shown. Wegovy is approved to reduce major cardiovascular events on the basis of a dedicated outcomes trial. CT-388 has no cardiovascular outcomes trial published and no such approval. For anyone with established cardiovascular disease this is the difference that decides the comparison.
What are CT-388's side effects compared with Wegovy's?
Wegovy's label reports every reaction above 2% by dose, including 44% nausea, 30% diarrhoea and 24% vomiting. CT-388's published safety data is one sentence describing adverse events as mostly mild or moderate, with no incidence figures at all. There is nothing to compare, in either direction.
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Where to read next
Not medical advice. This guide is for general education only. GLP-1 medications, dosing, and treatment suitability are decisions for you and a licensed clinician who knows your full medical history.