GLP-1 drugs and US military adherence

A retrospective cohort study published in Military Medicine on 9 July 2026 examined how 10,649 active duty US service members used GLP-1 receptor agonists for weight management between January 2021 and December 2025^[1]. The researchers compared three agents: liraglutide (Saxenda), semaglutide (Wegovy), and tirzepatide (Zepbound). What they found has implications for how military health planners, and clinicians more broadly, think about formulary selection when the goal is sustained weight management rather than short-term weight loss.

The study in brief

Miller and colleagues pulled pharmacy and medical records from the Military Health System database across a five-year window. All 10,649 participants were active duty service members who had initiated one of the three GLP-1 receptor agonists for weight management. The study measured two primary outcomes: adherence, defined as the proportion of days covered (PDC) over the first year, and persistence, defined as whether a service member was still on therapy at the 12-month mark^[1]. A Cox proportional-hazards model estimated discontinuation risk, adjusting for demographics including sex.

The headline numbers

Tirzepatide (Zepbound) led on both measures^[1]:

Annual proportion of days covered: Zepbound 78.2%, Wegovy 71.6%, Saxenda 48.7%.

One-year persistence: Zepbound 81.9%, Wegovy 70.7%, Saxenda 34.2%.

In the adjusted model, Zepbound was associated with a 33% lower discontinuation hazard compared with Wegovy. Saxenda, the liraglutide product and the oldest of the three, showed 26% higher discontinuation risk than Wegovy. Nearly two-thirds of service members on Saxenda had stopped treatment before the 12-month mark^[1].

The sex-based finding

The study found that male service members had a significantly higher likelihood of discontinuing GLP-1 therapy compared with female service members, across all three drugs^[1]. The authors did not attempt to identify the mechanism, and the database design limits causal inference. Possible explanations include differences in how weight management is perceived or stigmatised across sex in military culture, differences in access to follow-up care, or differences in the experience and reporting of gastrointestinal side effects, which are the dominant reason for early discontinuation in the broader clinical literature.

How adherence figures compare to the civilian literature

The adherence gap between tirzepatide and liraglutide in this military cohort mirrors what real-world studies in civilian populations have reported. A key reason is tolerability during dose escalation. Gastrointestinal adverse events, principally nausea, diarrhoea, vomiting, and constipation, are dose-dependent across the GLP-1 class and concentrated in the titration phase. Liraglutide is dosed daily and requires a six-week titration; weekly agents like semaglutide and tirzepatide generally show better adherence across studies, and the clinical trial data for tirzepatide suggests its gastrointestinal burden, while present, is managed across a slower escalation schedule than earlier GLP-1 drugs^[2].

The SURMOUNT-4 discontinuation trial, which followed adults on tirzepatide for weight management, showed that participants who stopped tirzepatide after an initial 36-week period regained a mean of 14.0% of their body weight over the following 52 weeks, while those who continued lost a further 5.5%^[3]. This weight-regain pattern after stopping reinforces why persistence data, not just short-term efficacy, matters for formulary and clinical decisions.

Why this population is worth studying separately

Active duty service members operate under fitness standards enforced by their branch of service. Weight and body-composition requirements are a condition of continued service, which creates a different motivational context than in civilian care. Military personnel may have both stronger external incentives to persist on therapy (fitness standards) and additional barriers (deployment cycles, operational tempo, access to follow-up care in the field). This study does not stratify by deployment status, military occupational specialty, or branch of service, so how those structural factors influenced the reported adherence numbers is not possible to determine from the published data^[1].

The Military Health System is also an integrated payer and provider system. Unlike fragmented civilian insurance markets, where continuity of coverage affects drug access, TRICARE-enrolled active duty members have continuous coverage. This means the adherence gaps observed here are less likely to be explained by lapses in insurance coverage than in civilian cohorts, making the persistence differences between the three drugs more likely to reflect drug-level factors.

Limitations of the study

The study is retrospective and observational. The three drugs were not prescribed under randomised conditions, meaning channelling bias, where prescribers selected specific agents for specific patients, cannot be excluded. Service members who received tirzepatide were prescribed a newer, more recently approved drug and may have been seen by prescribers with different practice patterns or patient communication styles than those prescribing liraglutide in earlier years^[1]. The time windows during which each drug was available differ, and the database may not capture prescriptions filled off-base or through civilian pharmacies.

The authors also note that the study reflects a specific population: active duty service members, who are younger, more physically active, and more predominantly male than the general adult population seeking weight management. Results may not generalise to veterans, dependents, or civilian patients.

What does not change based on this data

This analysis does not establish that tirzepatide produces better weight-loss outcomes than the other agents in this military cohort. It shows that service members who were prescribed Zepbound stayed on it longer and filled their prescriptions more consistently. Whether that persistence translated to greater weight reduction, improved fitness standards, or better metabolic outcomes is not reported. The efficacy case for tirzepatide in weight management comes from the randomised controlled trial evidence: SURMOUNT-5 (Aronne et al., NEJM 2025) reported a mean body-weight reduction of 20.2% on tirzepatide versus 13.7% on semaglutide 2.4 mg at 72 weeks^[4], which is a separate question from whether real-world users stay on the drug.

What we do not yet know

Several questions the study cannot answer: whether the sex-based discontinuation gap narrows or widens over longer follow-up; how adherence and persistence compare once tirzepatide reaches the full five-year period that Saxenda data already covers; whether the military-specific factors (fitness standards, deployment, chain-of-command culture) that might affect medication persistence are independent predictors when controlled for; and whether service members who persisted on therapy were more likely to meet their service branch's weight and fitness requirements. Those outcomes are the ones that military health planners and deployment-readiness officers would need before translating this adherence data into a formulary decision^[1].

This article is for educational and journalistic purposes only and does not constitute medical advice. GLP-1 receptor agonists are prescription medicines. Consult a qualified healthcare provider before starting, stopping, or changing any medication.