HealthIntel Weekly: GLP-1 Claims Surge 71% in Medicare Part D Between 2021 and 2023

Mar 27, 2026

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What’s New:

Total claims for GLP-1 medications increased by about 71% among beneficiaries enrolled in Medicare standalone Part D plans between 2021 and 2023, according to an Avalere Health analysis. Use was almost entirely limited to drugs approved for a Type 2 diabetes indication. The average number of GLP-1 claims per prescribing provider increased from 16.2 per provider in 2021 to 22.5 in 2023, driven primarily by growth in the average number of beneficiaries per provider with at least one GLP-1 claim, which rose from 4.4 in 2021 to 5.4 in 2023. GLP-1s also accounted for a growing share of these providers’ total Part D prescriptions, increasing from 3.2% in 2021 to 5.9% in 2023.

Enrollment in Medicare Advantage Institutional Special Needs Plans (I-SNPs) continued to rise from 2023 through 2026 even as the number of plans declined, according to a Milliman white paper. Growth was stronger in rural areas, where enrollment increased by about 13% compared to 4% in urban areas over the same period. UnitedHealth Group remained the largest I-SNP sponsor, though its market share fell from 57% in 2023 to 46% in 2026. Most I-SNPs offer premiums at or below the low-income premium subsidy amount. While Medicare Advantage plans often offer supplemental benefits beyond traditional Medicare, comprehensive dental coverage in the I-SNP market declined sharply. The share of beneficiaries with access to comprehensive dental through national carriers fell from 98% in 2025 to 56% in 2026. Special supplemental benefits for the chronically ill are widely offered, particularly by regional I-SNPs, with food and produce benefits most common in 2026, followed by nonmedical transportation and services addressing social needs.

Insurers of qualified health plans sold on HealthCare.gov denied roughly one in five in-network claims in 2024, according to a KFF analysis, with denial rates varying significantly across insurers and states. Three percent of reporting insurers had in-network denial rates of 30% or higher in 2024, down from 17% in 2023. Among insurers receiving more than 5 million claims, Oscar Health reported the highest in-network denial rate at 25%, while Elevance Health reported the lowest at 8%. The most common denial reason was “Other” (36%), followed by administrative issues (25%). Nine percent of denials were due to lack of prior authorization or referral, and only 5% were attributed to lack of medical necessity. Enrollees rarely appealed denied claims, and among those who did, insurers often upheld the original decision.