GLP-1 Drugs Raise Testosterone in Obese Men and May Preserve Fertility

Key takeaways

• A 2026 review (10 studies, 639 men) linked GLP-1 receptor agonists with higher total testosterone in men with obesity, diabetes, or functional hypogonadism, while preserving LH/FSH.
• Free testosterone changes were inconsistent—likely due to rising SHBG—so symptoms and comprehensive labs (total T, SHBG, LH/FSH) matter.
• Some obese cohorts showed improved semen parameters (motility, morphology, concentration), suggesting fertility-sparing potential versus TRT.
• TRT’s cardiovascular boxed warning was removed in 2025, but a class-wide blood pressure warning was added; careful monitoring remains essential.
• GLP-1s may be a first-line option for metabolic hypogonadism when fertility preservation is a priority; long-term data are still needed.

Overview

Men with obesity or type 2 diabetes often face a double challenge: low energy, low libido, and other symptoms of “low T,” plus the metabolic drivers that can keep testosterone down in the first place. Testosterone replacement therapy (TRT) is one way to relieve symptoms—but it can suppress fertility and requires ongoing monitoring. A 2026 systematic review suggests another path may help some men: GLP-1 receptor agonists (GLP-1RAs) such as semaglutide and liraglutide. These medications, widely used for weight loss and diabetes, were associated with meaningful increases in total testosterone—and, notably, preservation of gonadotropins (LH and FSH), which are essential for sperm production.

Below, we break down what the review found, where the evidence is strongest, and what it could mean for men weighing GLP-1s versus TRT.

What the 2026 Systematic Review Found

A January 2026 systematic review synthesized 10 studies (randomized trials and cohort studies) involving 639 men, most with obesity, type 2 diabetes, and/or functional hypogonadism. Across these studies, GLP-1RAs—primarily semaglutide and liraglutide—were associated with:

• Increases in total testosterone. The effect was most consistent in men with metabolic drivers of low T (obesity, insulin resistance).
• Preservation or rises in LH and FSH. Unlike TRT, which typically suppresses these pituitary hormones (and can reduce sperm production), GLP-1s appeared to maintain the hypothalamic–pituitary–gonadal (HPG) axis.
• Improvements in semen parameters in obese men, including motility, morphology, and concentration. These benefits did not extend to healthy, normal-weight controls—reinforcing that the signal is strongest in metabolic hypogonadism.
• Metabolic gains typical of GLP-1s: weight loss and lower HbA1c, both relevant to hormonal recovery. The review notes that weight loss on the order of 10% was associated with notable testosterone increases (e.g., approximately 53–77% in some cohorts), highlighting how body composition can track with androgen status.
• Mixed effects on free testosterone. Many studies documented increases in sex hormone–binding globulin (SHBG), which can keep calculated free T steady even as total T rises. Clinically, this means a lab-only focus on total T may over- or understate changes in bioavailable testosterone; symptom assessment and comprehensive labs (total T, SHBG, LH/FSH) offer better context.

Importantly, the studies were short-term and relatively small—a reason for caution and for ongoing trials to confirm durability, symptom relief, and safety over longer horizons.

Why This Matters for Men Considering TRT

TRT remains an effective therapy for men with confirmed hypogonadism and compatible goals. But it comes with trade-offs:

• Gonadotropin suppression: Exogenous testosterone typically lowers LH and FSH, which can reduce or halt sperm production. For men seeking future fertility, this is a central concern.
• Monitoring requirements: Routine checks for hematocrit, prostate health, and now blood pressure are part of responsible TRT care.
• Regulatory updates: In 2025, the FDA removed the cardiovascular boxed warning for testosterone after a large outcomes trial showed no increase in major cardiovascular events. At the same time, the FDA added a class-wide warning about blood pressure increases based on ambulatory monitoring studies. Careful selection and follow-up remain critical.

The 2026 review suggests GLP-1RAs may offer a fertility-sparing alternative for men whose low T is driven by obesity or insulin resistance. By reducing adiposity and improving insulin sensitivity—while preserving LH/FSH—GLP-1 therapy could address the root metabolic problem and allow the HPG axis to rebound.

For the TRT-curious, this raises a practical question: if fertility preservation is a priority, and if metabolic drivers are at play, could GLP-1s be a reasonable first step before committing to TRT? The answer will depend on diagnosis, goals, and close clinician guidance.

GLP-1 Testosterone Increase: How Might It Work?

Mechanistically, several threads likely converge:

• Weight loss reduces aromatase activity in adipose tissue, potentially curbing testosterone-to-estradiol conversion and easing negative feedback on the HPG axis.
• Lower inflammation and improved insulin sensitivity may restore hypothalamic and pituitary signaling, supporting endogenous testosterone production.
• Rising SHBG with weight loss can raise total T but sometimes mask changes in free T—explaining why symptoms may not always track with total T alone.
• Some studies observed LH/FSH preservation or increases, consistent with an intact central signal to the testes.

Open questions remain about whether GLP-1s also have direct, weight-independent effects on testicular or central pathways. The review calls for longer trials to tease apart mechanisms and clinical significance.

Who Might Benefit Most: Metabolic Hypogonadism vs. Primary Causes

The strongest signal for GLP-1–related testosterone gains appears in men with:

• Obesity and/or type 2 diabetes
• Functional (metabolic) hypogonadism, where excess adiposity and insulin resistance suppress the HPG axis but the system remains recoverable

In contrast, men with primary testicular failure (e.g., genetic or structural causes) or long-standing organic hypothalamic/pituitary disease may not respond similarly because the underlying problem is not predominantly metabolic.

Diagnosis matters. Clinical guidelines typically require two separate morning total testosterone measurements, taken under standardized conditions, combined with compatible symptoms before diagnosing hypogonadism. Since SHBG often changes during weight loss, measuring SHBG and calculated free T can add context to total T. Clinicians also assess LH and FSH to help differentiate central from primary causes.

Note that using GLP-1RAs to treat hypogonadism is currently off-label. Decisions should be individualized and made with a clinician who can interpret labs, symptoms, fertility goals, and cardiometabolic risk.

Practical Implications: What a Thoughtful Care Plan Could Look Like

While no single pathway fits everyone, clinicians caring for men with metabolic hypogonadism may consider frameworks like:

• Address metabolic drivers early. Calorie-aware nutrition, resistance training, sleep optimization, and reduction of excess alcohol can all support endogenous testosterone.
• Consider GLP-1 therapy when lifestyle alone is insufficient, particularly if obesity or diabetes are present—and fertility is a priority. The 2026 review suggests GLP-1s can raise total T and preserve LH/FSH while improving weight and glycemia.
• Track more than total T. Because SHBG often rises with weight loss, comprehensive panels (total T, SHBG, LH/FSH) plus symptom scales (e.g., AMS for aging male symptoms, IIEF for sexual function—used in the ongoing SEMAT trial) provide a clearer picture.
• Protect lean mass. Significant weight loss can come with lean mass loss. Resistance training, adequate protein, and periodic body-composition checks can help mitigate sarcopenia risk reported in some weight-loss contexts.
• Reassess need for TRT. If testosterone and symptoms recover on GLP-1s and lifestyle therapy, TRT may not be necessary. If not, or if fertility is no longer a priority, TRT can still be considered with appropriate monitoring.
• Plan for maintenance. Sustaining metabolic improvements is key to sustaining hormonal improvements. Stopping GLP-1s without a maintenance plan may allow weight regain and a slide in testosterone.

At Taurus Meds, our role is to help patients and their clinicians weigh these trade-offs, sequence therapies thoughtfully, and monitor progress with clarity.

Semaglutide vs. TRT: What the SEMAT Trial May Clarify

A head-to-head comparison is underway. The SEMAT trial (NCT06489457) is enrolling obese men with type 2 diabetes and hypogonadism (testosterone < 11 nmol/L) to compare semaglutide versus TRT over 24 weeks. The study will track:

• Testosterone (total and, in many designs, related markers like SHBG)
• Gonadotropins (LH/FSH)
• Sperm quality
• Symptom scales including IIEF-15 (erectile function) and AMS (aging male symptoms)

Results from SEMAT should help answer practical questions: How much symptom relief can semaglutide deliver relative to TRT in metabolic hypogonadism? How do sperm parameters differ? Does preserving LH/FSH translate to sustained fertility advantages? And what are the trade-offs in body composition and blood pressure?

Risks and Cautions: GLP-1RAs and TRT

GLP-1 receptor agonists

• Evidence base: The 2026 review draws from only 10 studies with 639 men—short-term and relatively small. Longer-term outcomes for testosterone, semen quality, prostate health, and cardiovascular endpoints remain unknown.
• Free vs. total T: Rising SHBG can make free T responses less predictable; clinical interpretation should be cautious and holistic.
• Fertility outcomes: Improvements in semen parameters were observed in obese men but not in healthy controls; generalizing to all men is premature.
• Body composition: Rapid weight loss can include lean mass loss; resistance training and nutrition are important safeguards.
• Regulatory status: GLP-1s are not approved for treating hypogonadism; use for this purpose is off-label and should be clinician-directed.

TRT

• Cardiovascular labeling: Following the TRAVERSE trial, the FDA removed the boxed cardiovascular warning in 2025, reflecting no increase in major adverse cardiovascular events versus placebo.
• Blood pressure: The FDA added a class-wide warning for increased blood pressure based on ambulatory blood pressure monitoring studies; careful monitoring is warranted.
• HPG axis suppression: TRT typically suppresses LH/FSH and can reduce sperm production—central for men planning future fertility.
• Monitoring: Hematocrit, prostate parameters, and symptom assessments are part of ongoing care. TRT is not indicated solely for age-related low T without confirmed hypogonadism.

The bottom line: select treatments based on a confirmed diagnosis, personal goals (including fertility), cardiometabolic risk, and a monitoring plan.

Liraglutide, Semaglutide, and Male Hormones: What Current Evidence Suggests

• Both liraglutide and semaglutide were linked with increases in total testosterone in men with obesity, type 2 diabetes, or functional hypogonadism.
• The largest and most consistent hormonal improvements tracked with meaningful weight loss and better glycemic control.
• Preservation (or elevation) of LH/FSH stands out as a differentiator from TRT—and as a plausible explanation for the semen-quality improvements reported in obese cohorts.
• Free testosterone responses vary, likely reflecting SHBG dynamics. This makes symptom-guided care and comprehensive labs important during treatment.
• While the GLP-1 testosterone signal is promising, proof of long-term symptomatic superiority or parity with TRT does not yet exist. The SEMAT trial and future RCTs will be pivotal.

A Balanced Conclusion

For men with obesity-related or diabetes-related low testosterone, GLP-1 receptor agonists offer a compelling, fertility-sparing avenue to raise total testosterone by addressing underlying metabolic stress. The 2026 systematic review strengthens the case that GLP-1s can increase total T while preserving gonadotropins and, in some obese men, improve semen parameters. That profile contrasts with TRT’s predictable suppression of LH/FSH and potential fertility impact.

Still, the evidence is early. The studies are small and short, free testosterone responses vary, and we lack long-term outcomes. TRT remains an effective, well-studied option for properly diagnosed hypogonadism, with important but manageable monitoring needs—now including attention to blood pressure.

For many men, especially those wishing to preserve fertility, a GLP-1–first strategy alongside lifestyle support may be worth discussing with a clinician before pursuing TRT. As head-to-head data arrive, care teams will be better positioned to personalize the path: GLP-1s, TRT, or a thoughtfully sequenced combination over time.

Taurus Meds supports evidence-led, individualized hormone care. If you’re exploring options, we can help you and your clinician structure testing, interpret results, and align treatment with your health goals and priorities.

Disclaimer

This article is for informational purposes only and does not provide medical advice. Do not start, change, or stop any medication or therapy based on this content. Consult a qualified healthcare professional for diagnosis and personalized treatment recommendations.

Sources

• Systematic review (2026) on GLP-1RAs, testosterone, and fertility markers
• SEMAT trial (NCT06489457): Semaglutide versus TRT in metabolic hypogonadism
• FDA testosterone information (TRAVERSE and labeling context)
• FDA class-wide labeling changes for testosterone products (blood pressure warning, 2025)