Racial and Ethnic Disparities in Medication Adherence Among Medicare Advantage Enrollees With Diabetes
Authors' conclusion
This retrospective cohort study of MA enrollees with diabetes found racial and ethnic disparities in diabetes medication adherence. Disparities in adherence to insulin or SGLT2 inhibitors and/or GLP-1 RAs were partially mitigated by Medicaid and prescription drug subsidies but less so by plan-level factors.
Study context
- Population
- Medicare Advantage enrollees with Part D coverage in 2019 and documented diabetes diagnosis (2017–2018) who filled ≥1 prescription for metformin, insulin, an SGLT2i or a GLP-1 RA in 2019; mean (SD) age 72.11 (8.85) years
- Participants
- 587,716 enrollees
- Exposure
- Black vs White and Hispanic vs White Medicare Advantage (MA) enrollees
- Blackn = 80,586
- White (Black–White analyses)n = 233,505reference
- Hispanicn = 83,116
- White (Hispanic–White analyses)n = 190,509reference
- Outcome
- Unadjusted and adjusted disparities in adherence (proportion of days covered ≥80%) for insulin, metformin, and SGLT2i and/or GLP-1 RAs
- Follow-up
- 2019
Methodological detailsOaxaca-Blinder decomposition analysis, Analysis conducted December 2024 to November 2025
- Oaxaca-Blinder decomposition analysis
- Analysis conducted December 2024 to November 2025
Main finding
As reported in the abstract
Unadjusted adherence disparities (proportion of days covered ≥80%)
- Black vs White (Black–White analyses)
- difference, SGLT2i and/or GLP-1 RAs −9.0 pp; P < 0.001
- Black vs White (Black–White analyses)
- difference, insulin −8.0 pp; P < 0.001
- Black vs White (Black–White analyses)
- difference, metformin −10.5 pp; P < 0.001
- Hispanic vs White (Hispanic–White analyses)
- difference, SGLT2i and/or GLP-1 RAs −8.1 pp; P < 0.001
- Hispanic vs White (Hispanic–White analyses)
- difference, insulin −2.8 pp; P < 0.001
- Hispanic vs White (Hispanic–White analyses)
- difference, metformin −3.6 pp; P < 0.001
Observational data: associations, not effects.
Further findings
Share of adherence disparities due to within-plan disparities, by medication type
- Black vs White
- 74.6% to 85.3%
- Hispanic vs White
- 39.1% to 66.1%
Reduction in disparities associated with Medicaid or Low-Income Subsidy enrollment
- Black vs White, insulin
- 22.0%
- Black vs White, SGLT2i and/or GLP-1 RAs
- 32.3%
- Hispanic vs White, insulin
- 63.9%
- Hispanic vs White, SGLT2i and/or GLP-1 RAs
- 41.3%
Original publication
Racial and Ethnic Disparities in Medication Adherence Among Medicare Advantage Enrollees With Diabetes. JAMA Netw Open. Published 1 September 2026. doi:10.
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