Most patients starting Wegovy or Zepbound now stay on them for a year, claims analysis finds

Nearly two-thirds of U.S. patients who started taking Wegovy or Zepbound in the first quarter of 2024 were still on one of the drugs 12 months later, according to an analysis of pharmacy claims by Prime Therapeutics shared with Reuters ^[1]. That is well above earlier estimates, which had hovered around one-third ^[1].

Prime, a pharmacy benefits manager owned by 19 U.S. Blue Cross and Blue Shield health plans, found that 63% of patients starting Novo Nordisk's Wegovy or Eli Lilly's Zepbound in early 2024 were still filling prescriptions a year later ^[1]. For Wegovy, persistence rose from 40% among patients who started in 2023 and 34% among those who began three years earlier ^[1]. Zepbound's one-year results were relatively unchanged year over year, though the drug did not launch until November 2023, so fewer patients were available to compare ^[1]. Wegovy was approved in June 2021 ^[1].

The year-over-year analysis covered 23,025 people with commercial health plans and a diagnosis of obesity. The mean age was 46 and 77% were female ^[1]. Patients with a diabetes diagnosis, or who were using one of these drugs for type 2 diabetes, were excluded ^[1]. Prime counted patients as persistent if they had no 60-day gap in supply, and it allowed switching between GLP-1 products ^[1]. Prescriptions for compounded versions and prescriptions paid for out of pocket outside insurance were not included ^[1].

The analysis does not include reasons why patients continued or stopped ^[1]. Prime and outside experts pointed to several possible factors: product shortages have eased, insurance coverage has expanded, and doctors have gotten better at managing side effects ^[1]. Some patients have reported stopping because the drugs became unaffordable, their insurance stopped covering them, they had common gastrointestinal side effects, they could not get refills during shortages, or they reached their weight-loss goal ^[1].

Over a longer window, the picture changes. In a separate analysis of 5,780 patients who stayed enrolled in their health insurance for three years and did not have type 2 diabetes, 14% were still taking Wegovy after three years, down from 24% at the two-year mark ^[1].

Patrick Gleason, Prime's assistant vice president for health outcomes and a co-author of the analysis, said the rise surprised him. "It's a near doubling from one-third persistent to roughly two-thirds now," he said. "This is a dramatic change, and I believe this is more reflective of what we will see going forward" ^[1].

Dr. Ezekiel J. Emanuel, co-director of the Healthcare Transformation Institute at the University of Pennsylvania, told Reuters that low persistence on these weight-loss drugs had been concerning and that the new data might indicate increased insurance coverage is helping turn the tide ^[1]. Novo Nordisk declined to comment on the data ^[1]. In a statement, Lilly said "Zepbound is intended to be prescribed by a doctor as part of a long-term treatment plan, alongside diet and exercise" ^[1].

Why it matters for patients

How long people stay on these drugs shapes what they get from them. Studies have shown that most patients who quit GLP-1 drugs usually regain most of the weight, and the medications may require extended use to yield meaningful health benefits ^[1]. The new numbers suggest that staying on treatment for at least a year is now the common experience among commercially insured patients, not the exception.

Cost and coverage remain the central open questions. Many employers and government agencies are still wary of adding coverage for these expensive medicines because of the upfront investment and uncertainty about future savings ^[1]. The FDA removed semaglutide, the active ingredient in Wegovy, from its shortage list earlier in 2025 and did the same for tirzepatide, the ingredient in Zepbound, in December 2024. Those moves eventually barred compounding pharmacies from making cheaper copies of the drugs ^[1].

The analysis does not measure health outcomes, and it does not explain why any individual stopped treatment. It also leaves out people who buy the drugs directly from the manufacturers outside their insurance. David Lassen, Prime's vice president of clinical pharmacy services, said that group "could have a different adherence pattern" and that it is "something we want to continue to watch" ^[1].

What is not yet known

Whether the one-year persistence rate holds for patients who pay cash or use compounded versions has not been reported ^[1]. The findings come from insurance claims rather than a clinical trial, and the data did not capture reasons for discontinuation ^[1]. Novo Nordisk has not commented on the analysis, and Lilly's statement did not address the persistence numbers directly ^[1].