Real-world evidence is what tells you whether a Phase 3 result holds up in routine care. Coverage on this site has leaned on Truveta's EHR network, IQVIA, and several academic registry analyses — particularly for GLP-1 outcomes outside trial conditions.
Key reads: the Truveta EHR analysis at OMA 2026 reproducing SURMOUNT-5's tirzepatide-vs-semaglutide signal at 12 months in routine care; the Mass General Brigham JAMA study of 90,000+ HFpEF patients on semaglutide and tirzepatide; the AAN 2026 living systematic review of GLP-1 dementia incidence in 2+ million diabetics; and the Foundayo IQVIA launch tracker through retail pharmacy.
Stories here cover the registry analyses, the Truveta and IQVIA data drops, and the policy implications. See #clinical-trial for trial-side coverage.
Real-world evidence for Wegovy (semaglutide 2.4 mg once weekly subcutaneous injection) documents 5.9% to 12% mean body weight reduction at 6 to 12 months across registry and claims analyses. This compares to 14.9% weight loss in the STEP-1 registrational trial that supported the FDA approval. The gap is primarily adherence-driven: missed doses, titration pauses, insurance-driven dose changes, and stop-restart cycles flatten real-world curves relative to the tight-adherence STEP-1 population. Cleveland Clinic research confirmed that injectable obesity medications produce smaller weight loss in a real-world setting compared to randomized clinical trials, with the gap larger in patient subgroups facing financial barriers to consistent supply. A large real-world study of nearly 8,000 patients who discontinued GLP-1 therapy found that most manage to keep the weight off or continue losing by restarting treatment, switching medications (typically to tirzepatide or higher-dose Wegovy), or adopting lifestyle changes. Patient satisfaction is driven primarily by perceived effectiveness rather than tolerability: effective weight loss even with gastrointestinal side effects is associated with continued treatment adherence, while lower-efficacy responses lead to early discontinuation regardless of tolerability. The real-world evidence has implications for retatrutide's likely commercial trajectory: the 28.7% Phase 3 ceiling may translate to 15-20% in real-world use depending on adherence patterns, which is still substantially above semaglutide's real-world 5.9-12% range.
A CROI 2026 (Conference on Retroviruses and Opportunistic Infections) analysis presented earlier in 2026 documented that GLP-1 weight-loss medications generally work well for people living with HIV who are stable on antiretroviral therapy. Beyond the known obesity and type 2 diabetes benefits, the CROI analysis reported potential improvements in liver, gut, and cardiovascular health, plus reduced smoking rates in the HIV population on GLP-1 therapy. Real-world analysis of people living with HIV prescribed semaglutide (Wegovy, Ozempic) or tirzepatide (Mounjaro, Zepbound) documented comparable weight loss to general-population Phase 3 trial data with no new safety signals specific to the HIV population. Approximately 40% of people living with HIV in the US also have obesity, and cardiovascular disease is one of the primary drivers of morbidity and mortality in the HIV-treated population. The CROI analysis supports GLP-1 therapy as a reasonable consideration in HIV patients with obesity or metabolic-syndrome comorbidities, particularly following the AIDS 2026 conference programming that concluded Friday July 31 in Rio de Janeiro emphasizing the sustained management of HIV alongside comorbid conditions in the current global funding-constrained environment. The finding also intersects with the ongoing peptide-adjacent HIV therapeutic landscape covered by the July 2026 Gilead-Merck ISLEND-1 and ISLEND-2 once-weekly islatravir/lenacapavir data and the Merck alimatravir monthly HIV prevention pill.
US data-analytics firm nference published a real-world evidence analysis this week that compared frailty-related outcomes across three cohorts of US adults 65 and older: nearly 30,000 patients treated with Zepbound (tirzepatide) for obesity, nearly 19,000 receiving non-GLP-1 drugs for type 2 diabetes, and nearly 6,000 who underwent weight-loss surgery. Health records showed progressive declines in muscle mass and function developed in 0.16% of patients across the analysis, malnutrition in 1.6%, dehydration in 3%, and loss of appetite in 4.75%. Lead author Soundararajan's team focused on Zepbound because prior analyses linked tirzepatide with more weight and muscle loss than semaglutide (the active ingredient in Novo Nordisk's Wegovy and Ozempic). The authors said results should not discourage appropriate use of Zepbound or Wegovy in older adults and encouraged closer follow-up of older patients on GLP-1 therapy. The findings arrive as the Medicare GLP-1 Bridge (launched July 1, 2026) expands GLP-1 access to Part D beneficiaries and as prescribers weigh muscle-preservation strategies including selective androgen receptor modulators (SARMs) like Veru's enobosarm and myostatin inhibitors.
Eisai and Biogen announced Tuesday July 14, 2026 that data from the real-world Lecanemab in Early Alzheimer's Disease (LEADER) Study, presented at AAIC 2026 in London during the Developing Topics Session '#3-33-DEV-A: Lecanemab Three Years Post-Approval: A Comprehensive Multicenter, Real-World, Retrospective Study (LEADER) in Diverse US Clinical Settings,' documented durable clinical outcomes with LEQEMBI in early Alzheimer's disease. The analysis included 432 early Alzheimer's disease patients from diverse US clinical settings who had received at least seven LEQEMBI infusions as of May 2026. Over an average of 17 months of treatment, 75.9% of patients remained clinically stable and 6.6% improved (moving from mild Alzheimer's disease dementia to mild cognitive impairment due to Alzheimer's disease). 87% of patients chose to remain on LEQEMBI treatment. Results were consistent across sex, race, ethnicity, and APOE genotype, supporting long-term benefits of continuous treatment outside of a controlled clinical trial setting.
The Conference on Retroviruses and Opportunistic Infections (CROI 2026, March 9-12) featured an oral plenary by Dr. Todd Brown of Johns Hopkins Medicine titled 'GLP-1 Agonists: Are They a Cure for Everything?' alongside one oral abstract and seven posters on the use of GLP-1 receptor agonists in people living with HIV (PLWH). The findings: GLP-1s generally work well in PLWH, may improve liver fibrosis, gut tissue immune health, and cardiovascular risk, and may reduce smoking on top of the established weight loss and diabetes effects. One oral abstract suggested potential to reverse the gut damage that persists from very early HIV infection despite effective ART. Brown's plenary concluded the enthusiasm is warranted but flagged unanswered questions around long-term use and global access — particularly relevant for PLWH in low- and middle-income countries.
An analysis of 60,000+ Americans with type 2 diabetes, presented at ENDO 2026 by Sainikhil Sontha (Boston University School of Public Health) and published in the Endocrine Society press release stream, found that 40% of GLP-1 users discontinued the medication within 12 months and roughly 60% had stopped by the end of two years. Among those who stopped, 41.5% restarted within a year and 58% within two years. Discontinuation was higher among Medicaid/Medicare beneficiaries, Black patients, and patients with documented nausea or GI side effects (37% of stoppers). Newer-generation tirzepatide users were 41% less likely to discontinue than liraglutide users, and patients whose first GLP-1 was prescribed by an endocrinologist were 10% less likely to stop. The data complement the Cleveland Clinic 8,000-patient real-world finding (March) and the eClinicalMedicine Budini meta-regression on weight-regain trajectory, sharpening the picture of how GLP-1 therapy churn actually unfolds in US insurance-claims populations.
A real-world comparison of tirzepatide and semaglutide for obesity by Venkatakrishnan and colleagues, published in PNAS Nexus on June 16, reported mean body-weight reductions of 14.7% on tirzepatide versus 10.8% on semaglutide at one year. The tirzepatide arm produced close to twice the proportion of 'high responders' (more than 15% body-weight loss) and lower rates of GI events, headache, and fatigue. Female and white patients responded more strongly on either drug than male, black, or Hispanic patients, who were more frequently in the under-5% weight-loss tier. The findings track with SURMOUNT-5's head-to-head trial result and the April 13 OMA Truveta poster but add a new demographic-disparity dimension that should inform real-world treatment selection.
A Stanford-led retrospective pre-post cohort study presented June 13 at ENDO 2026 in Chicago used NIH All of Us Research Program data linking electronic health records with Fitbit activity in 1,950 adults with obesity who started GLP-1 medications. Among the 753 with sufficient wearable data, mean daily steps dropped from 5,047 before GLP-1 initiation to 4,487 after (-560 steps, p<0.001); moderate-to-vigorous activity fell from 27.9 to 22.2 minutes per day (-5.7 minutes, p<0.001). The largest declines occurred in men and in people with pre-existing joint or muscle pain; age, heart failure, and stroke history did not change the pattern. Lead author Surya Maharjan flagged the activity drop as a concern given GLP-1-associated lean-mass loss.
Stanford University researchers presented retrospective cohort data at ENDO 2026 on June 13 from the Atropos Health Eos electronic health record dataset (~161 million patients seen in US community hospitals and academic medical centers, January 2016 to December 2023). Among adults with type 2 diabetes and no prior fractures or osteoporosis medication use, semaglutide was associated with a 15% lower fracture risk and greater weight loss versus other anti-obesity medications. Principal investigator Jairo Noreña framed the work as an early signal that semaglutide-driven weight loss may protect bone health in T2D, with prospective studies needed to confirm.
AJMC reported real-world claims data showing that 51.3% of patients on GLP-1 drugs carry at least one diagnosis tied to an emerging GLP-1 indication, 13.8% carry two, and 6.8% carry three or more. Obstructive sleep apnea led the comorbidity prevalence at 25.5%, followed by major depressive disorder at 18.2%, chronic kidney disease at 10.6%, and NAFLD/NASH at 10.3%. The numbers quantify the indication creep the field has been narrating since ADA: prescribers are increasingly writing GLP-1s for patients whose secondary conditions align with the expanding regulatory map (Wegovy CV, FLOW kidney, SURMOUNT-OSA, ESSENCE MASH).
A separate ASCO 2026 analysis examined outcomes in patients with breast cancer and co-existing obesity or type 2 diabetes who received GLP-1 receptor agonists — adding breast-cancer-specific depth to the broader GLP-1-and-cancer signal that ran through the meeting. The analysis sits alongside Abstract 3143 (the 12,112-patient study showing 38-50% lower metastatic progression across four obesity-related cancers, with breast cancer at 10% vs 20% metastasis on GLP-1 vs gliptin) and the Roswell Park aggressive-breast-cancer analysis. The consistent theme across the ASCO 2026 GLP-1 oncology slate: in obesity-related and metabolically-driven cancers, GLP-1 therapy appears associated with better outcomes, with the strongest and most mechanistically interpretable signal in breast cancer where high tumor GLP-1 receptor expression tracked with 45% lower mortality. Adverse-event rates matched the comparator groups with no increase in pancreatitis or other GLP-1-associated concerns in the cancer setting. The data is observational and not yet RCT-grade, but the breast-cancer consistency across multiple independent analyses strengthens the case for prospective study.
Roswell Park Comprehensive Cancer Center will present an analysis at ASCO 2026 (May 29-June 2 Chicago) by Dr. Zunairah Shah on the effects of GLP-1 receptor agonists in aggressive breast cancer. The real-world study examines whether GLP-1 therapy — widely used for glucose control and weight loss — confers additional benefit in high-risk breast cancer outcomes. The analysis joins the broader ASCO 2026 GLP-1 oncology slate, which includes Abstract 3143 (the 12,112-patient analysis showing 38-50% lower metastatic progression across four obesity-related cancers, with breast cancer showing 10% vs 20% metastasis on GLP-1 vs gliptin and 45% lower mortality with high tumor GLP-1R expression). Roswell Park also presented a companion real-world analysis on protein-energy malnutrition outcomes in metastatic TNBC (Abstract 1135). The GLP-1-and-cancer signal is one of the most-watched emerging themes at ASCO 2026, expanding the GLP-1 indication conversation beyond cardiometabolic disease.
Novo Nordisk extended its EASL 2026 ESSENCE presentation cycle into Day 2 with real-world evidence quantifying the MASH disease burden — documenting significant quality-of-life impairment and escalating healthcare costs in MASH patients — alongside the Japanese MASH and menopausal women subgroup analyses presented Day 1. The data builds the health-economic case for semaglutide 2.4 mg following the August 2025 FDA MASH-with-fibrosis approval. MASH affects roughly 1 in 3 people living with overweight or obesity worldwide, with the majority undiagnosed. Novo's 'Love Your Liver' EASL initiative offered on-site MASH testing for attendees. The real-world burden data complements the ESSENCE Phase 3 efficacy story by establishing the economic and quality-of-life rationale for early MASH intervention — a payer-facing argument as the GLP-1 MASH indication scales into 2026-2027 against the THR-β, FGF21, and GLP-1/glucagon competitor classes.
A real-world data analysis previewed at ASCO's May 26 embargoed press briefing compared GLP-1 receptor agonists against DPP-4 inhibitors (gliptins) across 12,112 patients with seven obesity-related cancers. For four of the seven — lung, breast, colorectal, and liver — patients on GLP-1s were 38% to 50% less likely to progress to stage IV cancer than patients on gliptins. Specific metastasis rates: lung 10% (GLP-1) vs 22% (gliptin), breast 10% vs 20%, colorectal 13% vs 22%, liver 19% vs 28%. High tumor GLP-1 receptor expression was associated with a 33% lower risk of death across all seven cancer types; the association was particularly strong in breast cancer (45% lower mortality). The data reframes GLP-1 therapy as a candidate cancer-prevention modality alongside the established cardiometabolic indications. Abstract 3143 will be presented at the May 29-June 2 ASCO Annual Meeting in Chicago.
An ECO 2026 analysis covered May 18 by ScienceDaily examined 89,718 patients starting GLP-1 therapy — 75.6% semaglutide, 17.5% tirzepatide, 6.9% liraglutide — and stratified BMI change at year one. In the first year, 27% reduced BMI by less than 5%, 22.4% by 5-10%, 14.1% by 10-15%, and 15.8% by ≥15%, while 20.8% actually gained weight. Greater weight loss correlated with larger reductions in obesity-related risk endpoints; patients who gained weight after starting treatment faced worse health outcomes than untreated comparators in several measures.
A second post-hoc analysis of STEP UP presented Tuesday found Wegovy 7.2 mg delivered consistent weight loss across reproductive life stages: 22.6% premenopausal, 19.7% perimenopausal, 19.8% postmenopausal, with 41.4% of premenopausal women hitting ≥25% loss. Waist-circumference reductions: 17.5%, 15.6%, 15.3% respectively. Separately, a real-world analysis of 34,000+ women showed that those taking Wegovy had a 42-45% lower migraine risk and a 25% lower depression risk starting six months in versus those on menopausal hormone therapy alone. The real-world data lands as observational signals that warrant prospective study — not as proof of causation — but reinforces the cardiovascular and quality-of-life narrative for the women's-health subgroup.
Real-world data presented in the ECO 2026 cycle counters the trial-based efficacy headlines: a Prime Therapeutics commercial claims analysis (cited in the May 2026 Managed Healthcare Executive cover story) found just 8.1% of members persisted with anti-obesity GLP-1 medications for three years. A separate 6-month Medicaid persistence analysis showed roughly 61% staying on treatment at six months. The high attrition is driven primarily by GI tolerability, insurance turnover, and out-of-pocket costs after step-edit programs. For newer agents like semaglutide and tirzepatide, post-discontinuation weight regain averages 0.8 kg per month — projecting return to baseline by ~1.5 years. PBM programs (Optum Rx Weight Engage, Rightway, MedImpact GLP-1 Benefit 360) are now embedding multidisciplinary support to lift persistence above the current floor.
Prof. John Wilding (University of Liverpool) and colleagues will present at ECO 2026 a real-world observational study tracking obesity-linked complication rates by degree of GLP-1-driven weight loss. In the year following GLP-1 treatment initiation, 27.0% of patients had BMI reductions <5%, 22.4% had 5-<10%, 14.1% had 10-<15%, 15.8% had ≥15%, and 20.8% gained BMI. Over a mean 11-month follow-up, patients with ≥15% BMI reduction had 37% lower osteoarthritis odds, 30% lower CKD odds, 69% lower OSA odds, and 32% lower heart failure odds versus those with 0-5% reduction (all statistically significant except heart failure). Incidence per 1,000 person-years: 21.4 OA, 21.1 CKD, 20.3 OSA, 3.9 HF. The data quantifies the value of pushing for deeper weight loss rather than cruise-control dosing.