Retatrutide, Testosterone and Libido: What the Studies Actually Measured
Separate testosterone, sexual desire and overall sexual-function findings, with a sourced semaglutide comparison and a paired-median calculation check.
FormBlends Editorial Research · Updated 2026-10-03
Retatrutide is investigational and is not FDA-approved. FDA states that it cannot be used in compounding under federal law. FormBlends does not prescribe, compound or sell retatrutide.
The selected retatrutide obesity trials do not establish a testosterone or libido effect. A small trial of semaglutide did measure testosterone and sexual-function questionnaires in men with obesity, type 2 diabetes and functional hypogonadism. Its hormone result, sexual-desire result and overall questionnaire result differ, and none is a retatrutide result.
What evidence actually measures testosterone or desire?
We checked the primary and secondary registered outcome-measure lists for retatrutide studies NCT04881760 and NCT05929079 on October 3, 2026. Neither list names testosterone, libido or a sexual-function questionnaire as its outcome measure. This is a check of these two efficacy-outcome lists, not every study or every safety event.
TRIUMPH-2 included 598 men among 1,152 adults with obesity and type 2 diabetes, with primary weight assessment at 80 weeks. Male enrollment and weight reduction do not provide an unmeasured libido result.
The semaglutide study: separate the three findings
Gregoric and colleagues randomized 25 men to semaglutide or testosterone replacement in an open-label, 24-week trial. Thirteen received semaglutide and 12 received testosterone. These participants already had obesity, type 2 diabetes and functional hypogonadism; this was not an unselected adult population.
| Measurement | Baseline median | 24-week median | Within-group P value |
|---|---|---|---|
| Total testosterone, nmol/L | 6.1 | 7.8 | .023 |
| IIEF-15 sexual-desire score | 4 | 6 | .009 |
| IIEF-15 total score | 31 | 44 | .17 |
Source: published Tables 1 and 3. Sexual desire improved significantly in this group; the overall IIEF-15 score did not. The authors report no significant between-group differences in the IIEF-15 comparisons. Those statements describe different comparisons, rather than a contradiction.
Why subtracting the two medians can mislead
The total-score medians change from 31 to 44, an arithmetic difference of 13. But Table 3 reports a median individual change of 3. The total-testosterone medians differ by 1.7 nmol/L, while Table 1 reports a median individual change of 1.6 nmol/L.
A group's middle baseline value and middle follow-up value need not come from the same person. Subtracting those two group medians therefore need not equal the middle of the individual paired changes. That distinction matters when a headline presents a before-and-after table as a typical person's improvement.
The number 13 is neither a percentage improvement in libido nor the study's median paired total-score change. A sexual-desire subscore and a questionnaire's total score also measure different things. Keep the published paired-change column and the named endpoint beside the headline.
Does higher testosterone establish improved sexual function?
A hormone concentration is a laboratory measurement. Sexual desire and the broader questionnaire are participant-reported measurements. This trial supplies an example of why one cannot stand in for another: its semaglutide-group total-testosterone and sexual-desire findings reached statistical significance, while its overall IIEF-15 change did not.
The study does not identify whether an effect was mediated by weight change, another metabolic change or a direct receptor effect. A plausible mechanism is a research question, rather than a measured retatrutide outcome.
How to compare a retatrutide libido claim with its source
- Check the actual drug: a semaglutide finding cannot be renamed retatrutide.
- Check the population: functional hypogonadism with obesity and diabetes is a specific entry profile.
- Identify the outcome: total testosterone, desire, erectile function and total score are separate measurements.
- Identify the comparison: before-and-after within one group differs from a between-group result.
- Use the reported paired-change statistic when describing an individual's change.
Frequently asked questions
Does retatrutide boost testosterone?
The selected retatrutide publications and registered efficacy outcomes do not establish that effect. The semaglutide trial provides context for a different intervention.
Did semaglutide improve libido in the small trial?
Its sexual-desire subscore improved significantly in the semaglutide group. That finding did not establish significant improvement in the overall IIEF-15 score or a retatrutide effect.
Does the overall-score result prove there was no benefit?
No. A result that does not reach statistical significance in a small trial is not proof of no effect. The measured estimate, variability, comparison and sample size all belong in its interpretation.
The sources here do not establish retatrutide as an approved treatment for this population or condition. Eligibility for research is determined by the individual protocol, not by a website BMI calculator or a telehealth assessment. No personalized suitability or adjustment of other treatment can be inferred from this article.