GLP-1/GIP Uptake, Indication, and Access Pathways Among US Adults in the Understanding America Study

Evidence on GLP-1/GIP therapies is largely derived from trials enrolling selected populations or medical records that miss utilization outside healthcare channels. No nationally representative cohort has characterized real-world uptake, indications, and access.

To characterize GLP-1/GIP prevalence, indication, clinical profile, and access.

Prospective cohort study with three GLP-1/GIP surveillance waves (March 2024, December 2024, October 2025).

The Understanding America Study, an address-based, nationally representative panel of approximately 15,000 US adults aged 18+ years initiated in 2014.

UAS participants responding to at least one surveillance wave (n=9150).

GLP-1/GIP use status (never vs any use, comprising current and former use), self-reported primary indication (diabetes, weight loss, or other), and access pathway (traditional vs non-traditional).

Survey-weighted prevalence of GLP-1/GIP use, overall and by indication and access pathway; sociodemographic, cardiometabolic, treatment, and access characteristics; and smartwatch-derived resting heart rate, heart rate variability, maximum activity heart rate, step count, and sleep duration and variability.

Among n=9150 adults (1274 with any use; 60.9% female; median age 53 years), weighted prevalence increased 46%, from 8.2% (March 2024) to 12.0% (October 2025) representing 32 million. Weight-loss indications grew, reaching nearly half of use (4.1% to 5.6%); diabetes-indicated use was stable (5.3% to 5.4%). Users carried high cardiometabolic burden (obesity, 68.2%; diabetes, 53.6%) but diverged by indication: diabetes-indicated users were older (median, 59 vs 49 years), whereas weight-loss-indicated users were more often female (69.9% vs 51.3%) and healthier. One in three users (~9 million) had non-traditional access, especially in weight-loss-indicated users, of whom 33% had no conventional prescription; 41% used compounding, online, or foreign pharmacies; and, 43% lacked coverage. Non-traditional users were five times as likely to report an unlisted, likely compounded formulation (19.8% vs 4.1%). All p<0.05.

Real-world GLP-1/GIP use has grown rapidly and diversified substantially in indication, access, and population profile. One in 3 users obtained treatment through nontraditional channels largely invisible to claims data, raising long-term safety, efficacy, and coverage questions. GLIMMER provides a public, nationally representative longitudinal evidence base for future payer and provider decisions.

Question: Who is using glucagon-like peptide-1 receptor agonists or glucose-dependent insulinotropic polypeptides (GLP-1/GIP) therapies in the US, how has use changed since 2024, and how are these medications obtained?Findings: In this cohort study of 9150 US adults, GLP-1/GIP use rose significantly from 8.2% to 12.0% (March 2024-October 2025), driven by weight loss; those treated for diabetes were a decade older, lower-income, and in poorer health than those treated for weight loss. Overall, 1 in 3 users obtained treatment outside conventional prescribing and dispensing channels.Meaning: A large and growing share of GLP-1/GIP exposure occurs outside the channels visible to claims-based surveillance.