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.