GLP-1 obesity prescriptions: the fill gap
A 2026 real-world study examines which patient factors predict whether a semaglutide or tirzepatide prescription is actually filled.
Why we wrote this. Getting a prescription written is not the same as getting the drug. The fill gap is a distinct policy problem that most access coverage skips over.
In this article (6 sections)
Getting a prescription for semaglutide or tirzepatide is not the same as actually receiving the drug. A letter published in Diabetes, Obesity and Metabolism on 10 August 2026 by Mahip Acharya and Deboleena Thakur of the University of Arkansas for Medical Sciences examines who, among patients who already have a prescription order, goes on to fill it, and who does not[1].
The distinction matters because most of what we know about access barriers focuses on the upstream question: who gets prescribed at all. The Acharya and Thakur analysis targets the downstream gap, the step between prescription order and dispensed medication, which is a different failure point that existing policies do not always address.
What the study found
The analysis drew on real-world data to identify patient-level characteristics associated with not filling a prescription for semaglutide or tirzepatide after a prescription order was placed. The paper is published as a letter (not a full research article), so the methods are condensed, but the keyword set in PubMed identifies it as a population study using real-world evidence[1].
The full text is behind a paywall and the abstract is not publicly available on PubMed at the time of writing, which limits how much specific numerical detail can be verified independently. The framing below reflects the study's stated scope and the pattern of findings visible in the reference list and keyword tagging.
The upstream picture this study sits inside
To read the Acharya and Thakur findings in context, it helps to understand the broader initiation gap. A 2025 study in JAMA Network Open by Podolsky and colleagues examined 97,456 commercially insured US adults with obesity and without diabetes[2]. Only 2.0% of them initiated semaglutide within six months of an obesity diagnosis, despite FDA approval for weight management since 2021. The strongest predictors of initiation were female sex (adjusted odds ratio 2.30), use of antidepressants (aOR 1.62), and point-of-service insurance coverage (aOR 1.78).
A separate 2025 study in Diabetes, Obesity and Metabolism by Radwan and colleagues tracked 319,949 eligible adults in Florida and found similarly low uptake: only 1.8% initiated newer anti-obesity medications over a decade-long observation window[3]. Black patients had 13% lower odds of initiation versus White patients; Hispanic patients had 16% lower odds; Medicaid recipients had 31% lower odds compared to those with private insurance.
These two studies capture who starts the drugs. Acharya and Thakur's paper asks a narrower question: among the patients who reach the prescription step, what determines whether they follow through?
Why the fill gap is a distinct problem
A prescription order leaving the clinic is not a guarantee of access. Several factors can interrupt the chain at the pharmacy step. Cost is the most frequently cited: semaglutide (Wegovy) and tirzepatide (Zepbound) carry US list prices above $1,000 per month before manufacturer coupons or insurer negotiation. Prior authorization requirements, formulary restrictions, and insurance plan type all filter which patients can convert an order into a fill. Supply shortages, which were significant for semaglutide between 2022 and 2024, also created fill failures that had nothing to do with patient behavior.
The Podolsky analysis found that insurance plan type was one of the strongest predictors of initiation, which points to the same structural layer. If plan type predicts whether patients start the drug at all, it likely also predicts whether they can fill a prescription once written.
What the geography and demographics signal
The Radwan regional analysis found that uptake was concentrated in major urban centers (Miami, Orlando, Tampa, Jacksonville in the Florida dataset) and sparse in rural areas[3]. Rural pharmacy access is a compounding variable: fewer specialty pharmacies, longer distances to the dispensing point, and less exposure to the insurance plan types most associated with coverage. A patient in a rural county who receives a prescription order at a telehealth visit may face a fill barrier that a patient in a major metropolitan area does not.
The Acharya and Thakur paper is affiliated with the University of Arkansas for Medical Sciences, which suggests the analysis may draw on data from Arkansas or surrounding states, a region with a higher proportion of Medicaid-covered and uninsured patients than the national average. If so, the fill-gap findings likely sit at the harder end of the access spectrum.
What this does not tell us
Because the full text is not accessible without a journal subscription, specific effect sizes and the precise patient factors identified by Acharya and Thakur cannot be verified here. This article should be treated as contextual framing for a finding that warrants independent follow-up once the paper becomes more accessible, rather than as a summary of its numerical conclusions.
The persistence question, whether patients who do fill continue filling, is addressed by a separate 2026 claims study covered in Tirzepatide: 6-month US persistence data. That study found 68% of initiators remained persistent at six months, with lower adherence rates among those who had larger prior-authorization burdens.
What to watch
The fill-gap question will become more policy-relevant as coverage decisions expand. The Inflation Reduction Act provisions on Medicare obesity drug coverage, if implemented, would shift the insurance landscape significantly. Whether broader coverage translates into narrower fill gaps will require exactly the kind of real-world analysis Acharya and Thakur are conducting. For per-country access details, see the tirzepatide regulation pages and the semaglutide regulation pages.
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Frequently asked
Why would someone have a semaglutide or tirzepatide prescription but not fill it?
Several factors can prevent a fill after a prescription order is placed. Cost is the most frequently cited: US list prices for both drugs exceed $1,000 per month without insurance coverage. Prior authorization requirements, formulary restrictions, insurance plan type, and pharmacy availability also play a role. Supply shortages, which affected semaglutide availability between 2022 and 2024, created additional fill failures unrelated to patient choice.
How rare is it for eligible patients to actually start these drugs?
Very rare by the standards of the patient population that could benefit. A 2025 JAMA Network Open study found that only 2.0% of commercially insured US adults with obesity initiated semaglutide within six months of diagnosis. A separate 2025 study in Diabetes, Obesity and Metabolism found only 1.8% of eligible Florida adults initiated newer anti-obesity medications across a decade-long window.
Do race and insurance type affect whether patients fill GLP-1 prescriptions?
The available evidence on the initiation step suggests yes. The Radwan et al. 2025 study found Black patients had 13% lower odds and Hispanic patients 16% lower odds of initiating GLP-1 medications compared to White patients. Medicaid recipients had 31% lower odds versus the privately insured. Whether these disparities persist at the fill step specifically is what studies like the Acharya and Thakur 2026 paper are designed to clarify.
If a patient fills a prescription, do they stay on the medication?
Roughly two-thirds do, at least for six months. A 2026 claims study of 22,512 US tirzepatide initiators found 68% remained persistent at six months, defined as no gap longer than 45 days between fills. Adherence at the higher threshold of 80% of days covered was lower, at 55%. These figures come from a dataset of patients who succeeded in filling initially, so they do not capture those who never filled.
Sources
- [1]Acharya M, Thakur D. Prescribed but Not Filled: Patient Factors Related to Semaglutide/Tirzepatide Prescription Fills Among Those With Prescription Orders for Obesity Treatment. Diabetes Obes Metab. 2026 Aug 10. PMID 42575862Tier 1 · primary↩
- [2]Podolsky MI, Raquib R, Shafer PR, et al. Factors Associated With Semaglutide Initiation Among Adults With Obesity. JAMA Netw Open. 2025;8(1):e2455222. PMID 39836425Tier 1 · primary↩
- [3]Radwan RM, Lee YA, Kotecha P, et al. Regional Trends and Disparities in Newer GLP1 Receptor Agonist Initiation Among Real-World Adult Patients Eligible for Obesity Treatment. Diabetes Obes Metab. 2025;27(6):3113-3123. PMID 40035205Tier 1 · primary↩
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