Men with obesity and type 2 diabetes often have low testosterone, and the standard fix is to give them testosterone. That fix has a known cost: it suppresses the hormonal signal that tells the testes to make sperm. A man who wants both the symptom relief and the fertility is stuck. This trial asked whether a weight-loss drug could be the way out.
The trial
Twenty-five men with type 2 diabetes, obesity and functional hypogonadism were randomized to semaglutide 1 mg a week or intramuscular testosterone undecanoate 1000 mg every ten to twelve weeks, for 24 weeks, open-label. [1] Median age was 50 and median BMI 35.9. Semen analysis and hypogonadism measures were taken at baseline and at the end, alongside two questionnaires: the International Index of Erectile Function and the Aging Symptoms in Men scale.
Baseline semen quality was poor in both arms — below the 5th percentile of reference values. That matters for reading everything that follows. These were not men with normal parameters, and the trial is small enough that the usual gap between a trial and a clinic is the least of its limits.
What changed
In the semaglutide arm, the median proportion of morphologically normal sperm rose from 2% to 4%, p=0.012. In the testosterone arm, sperm concentration and total sperm number both fell significantly. Compared head to head at 24 weeks, the semaglutide group had significantly more morphologically normal sperm, higher concentration and a higher total count.
Both arms saw total testosterone rise and both improved on the Aging Symptoms scale. Only the testosterone arm improved significantly on erectile function.
What the numbers actually say
The within-arm change on semaglutide is the part that stands on its own, and it is small. A median of 2% morphologically normal sperm became 4%. Doubling sounds substantial; two percentage points, from a number already below the reference range to another number below the reference range, is a different impression of the same fact. Both are true and only printing the first would be selling.
Twenty-five men, split two ways, is twelve or thirteen per arm. Open-label means everyone knew which drug they were on, and the two regimens are impossible to confuse — a weekly self-injection against a deep intramuscular shot every few months. The design could not have blinded this. Those are the same questions worth asking of any small uncontrolled study, and here at least there was randomization and a comparator.
Why the comparator was chosen anyway
Because it is the clinical alternative. A trial is supposed to answer the question a doctor actually faces, and the question here is what to give a man with functional hypogonadism who would like to remain fertile. Against that question, testosterone is the right comparator and the result is genuinely useful. Against the question "does this drug improve sperm", it is the wrong one — and which question a comparator answers is the thing most summaries drop first.
A placebo arm would settle it. There was not one.
What a buyer should do with this
Nothing on this roster is sold for fertility, and no seller claims it. If male fertility is the actual goal, that is a reproductive endocrinologist’s question and semen analysis is the measurement — not a weight-loss intake form. What this trial supports is narrower: for a man already facing a choice between these two treatments, the semen parameters point one way and the erectile function score points the other.
The broader sexual-function evidence is thin and covered separately. What sellers say about any of it is close to nothing, which the census of silence counts directly.