Peptide trials by study population
Before putting results next to one another, I want the entry conditions on the table. The differences between the people can be as consequential as the differences between the molecules.
People enrolled
This is the part of a comparison I would pin to the fitting-room wall. Diabetes, established cardiovascular disease, fatty liver and dialysis describe different starting places. They change the questions a trial can answer and the risks participants already face.
| Study | Participants | Finding examined |
|---|---|---|
| STEP 1 | Overweight or obesity; no diabetes | Semaglutide and weight change |
| SELECT | Existing cardiovascular disease; excess weight; no diabetes | Semaglutide and major cardiovascular events |
| FLOW | Type 2 diabetes and chronic kidney disease | Semaglutide and major kidney-disease events |
| SURPASS-2 | Type 2 diabetes | Tirzepatide versus semaglutide for blood sugar and weight |
| Retatrutide liver substudy | Overweight or obesity with fatty liver | Liver fat on scans |
| MOTS-c cohort | Chronic hemodialysis | Natural blood levels and subsequent health events |
The last row is observational. A researcher measured what was already circulating and watched what happened later. In the treatment trials, participants actually received the study medicine or a comparator. Mixing those designs into a single benefits list would erase the question each study asked.
Tirzepatide versus semaglutide
SURMOUNT-5 gives tirzepatide and semaglutide a shared setting: adults with obesity, without type 2 diabetes, followed for 72 weeks. Mean weight change favored tirzepatide, −20.2% versus −13.7%.
My confidence is much greater in that comparison than in one assembled from the largest percentage reported for each compound. Retatrutide's 48-week Phase 2 obesity result belongs to a different trial. Its −24.2% highest-amount group mean cannot establish superiority over medicines tested elsewhere. The MOTS-c mouse performance results concern another species and another outcome again.
A common trial gives a comparison shared conditions. It still leaves variation within each group.
The individual fitting
An average collapses many responses into one value. It cannot tell us whether the same people would respond well to a different medicine, or how a person's other illnesses and medicines would alter the balance. Trials can establish group differences while leaving those individual predictions uncertain.
Tolerability adds another measurement. Semaglutide's safety review, tirzepatide's trials and retatrutide's early obesity trial all describe gastrointestinal problems. Retatrutide also brought pulse increases. A benefit that depends on continued treatment has to be considered alongside the difficulty of continuing it.
I want future comparisons to explain more of the variation: who stopped, which illnesses were present, and how those circumstances related to the outcomes. Until then, a clinician's assessment of a particular person supplies information a published average cannot. The name on this website offers no shortcut around that work.