Medicare Part D formulary coverage of SGLT2 inhibitors across cardiovascular-kidney-metabolic indications, 2019–2026

Purpose Sodium-glucose cotransporter-2 inhibitors (SGLT2i) carry Class I, Level A recommendations for type 2 diabetes (T2D), heart failure (HF), and chronic kidney disease (CKD) but remain underused outside T2D, with formulary restrictions commonly cited as a contributing cause. We assessed whether Medicare Part D formulary restrictions account for this gap and whether the restrictions differ across cardiovascular-kidney-metabolic (CKM) indications. Methods Cross-sectional analysis of national Medicare Part D formulary files for plan years 2019–2026, using the January/February snapshot (410 formularies in 2019, 330 in 2026; 13,726 SGLT2i monotherapy entries). We measured entry-level prior authorization (PA) and step-therapy prevalence, the proportion of formularies offering at least one and at least two unrestricted SGLT2i drugs, and tier distribution, across three indication groups reflecting cumulative regulatory approvals. Results PA was uncommon across all indications and years, never exceeding 1.6%, and at least 98% of formularies offered a PA-free SGLT2i in every indication group-year. Step therapy fell to zero by 2025 then rebounded in 2026, concentrated on empagliflozin, whose entry-level step therapy rate rose from 0.00% to 18.18%, coincident with the effective date of its negotiated maximum fair price; co-negotiated dapagliflozin showed no comparable increase (1.21%). Tier 3 was the dominant placement (61.9–78.7%). Canagliflozin coverage fell from 58.3% of formularies in 2019 to 5.8% in 2026, and only 5.8% offered two step-free SGLT2i for CKD by 2026. Conclusion Formulary restrictions do not appear to be a major barrier to SGLT2i use among Medicare beneficiaries, redirecting attention toward clinician- and system-level factors. Narrowing CKD-indication approved options and an emergent step-therapy rebound warrant monitoring.