GLP-1 Receptor Agonist Coverage for Obesity in Medicaid and Total GLP-1 Receptor Agonist Utilization.

IMPORTANCE: Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are effective for treating obesity, but few Medicaid programs cover them due to cost concerns with accelerating utilization. However, potential substitution effects between obesity-labeled GLP-1 RAs and diabetes-labeled GLP-1 RAs, which have identical active ingredients and which all states cover, are not well understood. OBJECTIVE: To determine whether Medicaid coverage of obesity-labeled GLP-1 RAs is associated with obesity-labeled, diabetes-labeled, and total GLP-1 RA utilization. DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional study used US state-level Medicaid drug utilization data from 2021 to 2024. Synthetic difference-in-differences was used to assess the association of obesity-labeled GLP-1 RA coverage with GLP-1 RA utilization. EXPOSURE: Medicaid program coverage of obesity-labeled GLP-1 RAs. MAIN OUTCOMES AND MEASURES: The primary outcome was aggregate quarterly prescriptions per 1000 beneficiaries; secondary outcomes included prescription-months (accounting for duration of fills) and Medicaid reimbursement per 1000 beneficiaries. RESULTS: Of 9 states (n = 89 021 657; mean [SD] of 49.4% [0.5%] were male, 50.6% [0.5%] were female) that began Medicaid coverage of obesity-labeled GLP-1 RAs between 2021 and 2024 and 36 control states (n = 212 786 953; mean [SD] of 49.8% [0.9%] were male, 50.2% [0.9%] were female), overall and diabetes-labeled GLP-1 RA utilization increased substantially in both groups, whereas obesity-labeled GLP-1 RA increased significantly only in treated states. Estimates from synthetic difference-in-differences models demonstrated a mean increase in obesity-labeled GLP-1 RA of 6.48 prescriptions per 1000 beneficiaries (95% CI, 4.00-8.96; P < .001), with estimates increasing nearly each quarter after Medicaid coverage was implemented. By contrast, changes in total GLP-1 RA prescriptions compared with obesity-labeled prescriptions were not statistically significant (4.17 per 1000 beneficiaries [95% CI, -0.33 to 8.67; P = .07]), nor were those for diabetes-labeled GLP-1 RA prescriptions (-2.16 prescriptions per 1000 beneficiaries [95% CI, -5.27 to 0.96; P = .17]). In the subgroup of states with prior authorization requirements more restrictive than the Food and Drug Administration label, there was a significant relative decrease in diabetes-labeled GLP-1 RA utilization of 3.02 prescriptions per 1000 beneficiaries (95% CI, -5.69 to -0.36; P = .03). CONCLUSIONS AND RELEVANCE: Results of this study suggest that substitution effects are possible between obesity-labeled and diabetes-labeled GLP-1 RAs, varying by state coverage policies, that could impact coverage decisions.