(158) Understanding GIP/GLP-1 Treatment Dynamics: Switching and Re-initiation in Medicare Advantage Beneficiaries

Background: : Despite growing use of glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1 receptor agonists (GIP/GLP-1 RA) for type 2 diabetes and obesity, persistence to initial therapy remains low. Among older adults, real-world data on treatment progression is limited. Drug shortages and the perceived clinical benefits of newer agents may further drive movement between GIP/GLP-1 RA agents.

Objective: : To describe treatment progression between GIP/GLP-1 RA agents, including switching and re-initiation patterns among Medicare Advantage beneficiaries over 1-year follow up.

Methods: : This retrospective cohort study used the Humana Research Database to identify patients who newly initiated semaglutide, tirzepatide, or other GLP-1 RAs (dulaglutide, liraglutide, exenatide) in 2023 (first prescription=index). Treatment progression was defined as any post-index prescription for a different GIP/GLP-1 RA agent. We described the proportion who switched between GIP/GLP-1 RA agents, those who reverted to their original treatment and the duration of use on each therapy.

Results: : Among 77,745 new GIP/GLP-1 RA users in 2023, 62.4% started on semaglutide (mean age: 67.4 years; 62% female), 20.7% on tirzepatide (mean age: 66.2 years; 62% female), and 16.9% on other GLP-1 RAs (mean age: 68.3 years; 57% female). Semaglutide initiators had an average duration on therapy of 4.7 months and 6.9% switched to tirzepatide. Following a mean of 4.1 months on tirzepatide, 11.4% re-initiated semaglutide. Tirzepatide initiators had an average duration on therapy of 4.6 months and 10% switched to semaglutide. Following a mean of 3.5 months on semaglutide, 22.1% re-initiated tirzepatide. Switching to other GLP-1-RAs from semaglutide (2.2%) or tirzepatide (1.9%) was less common, but patients had high rates of re-initiation of index therapy (18.6% for semaglutide, 20.5% for tirzepatide). Patients who initiated other GLP-1-RAs had higher rates of switching to both semaglutide (12.5%) and tirzepatide (7.3%) and longer mean duration on therapy following the switch, but lower rates of returning to index therapy (5.3%-7.2%) compared to the other cohorts.

Conclusions: : Switching between GIP/GLP-1 RA agents was common. Tirzepatide and semaglutide initiators who switched therapies had a high rate of index therapy re-initiation, indicating that patients may have substituted an available GIP/GLP-1 RA therapy during ongoing drug shortages. Further research can explore underlying factors for switching behaviors and their impact on patient outcomes.

Sponsorship:: None