Consequences of forgoing prescription drug subsidies among low-income Medicare beneficiaries with diabetes

Health Serv Res. 2022 Oct;57(5):1136-1144. doi: 10.1111/1475-6773.13990. Epub 2022 Apr 27.


Objective: The objective is to estimate the take-up of the Medicare Part D Low-Income Subsidy (LIS) among Medicare beneficiaries with diabetes and examine differences in out-of-pocket costs and prescription drug use between LIS enrollees and LIS-eligible non-enrollees. The LIS reduces out-of-pocket drug costs for low-income beneficiaries; however, not all LIS-eligible individuals are enrolled. Take-up of the LIS, and consequences of forgoing this benefit among beneficiaries with diabetes, remains unknown.

Data sources: Health and Retirement Study linked to Medicare administrative data from 2008 to 2016.

Study design: We conducted two analyses among beneficiaries with diabetes. First, we estimated LIS take-up stratified by income (≤100% of the Federal Poverty Level [FPL] and >100% to ≤150% of FPL). Second, to assess the consequences of forgoing the LIS among near-poor beneficiaries (incomes >100% to ≤150% of FPL), we conducted propensity score-weighted regression analyses to compare out-of-pocket costs, the prescription drug use, and cost-related medication non-adherence among LIS enrollees and LIS-eligible non-enrollees.

Data collection/data extraction: N/A.

Principal findings: Among Medicare beneficiaries with diabetes, 68.1% of those with incomes >100% to ≤150% of FPL received the LIS, while 90.3% with incomes ≤100% of FPL received the LIS. Among near-poor beneficiaries, LIS-eligible non-enrollees incurred higher annual out-of-pocket drug spending ($518; 95 [in USD]% CI: $370 [in USD], $667 [in USD]; p < 0.001), filled 7.3 fewer prescriptions for diabetes, hypertension, and hyperlipidemia drugs (95% CI: -11.1, -3.5; p < 0.001), and were 8.9 percentage points more likely to report skipping drugs due to cost (95% CI: 0.3, 18.0; p = 0.04), all compared to LIS enrollees.

Conclusions: Despite providing substantial financial assistance with prescription drug costs, the LIS is under-utilized among beneficiaries with chronic conditions requiring routine medication use. As policy makers discuss Part D reforms to address rising out-of-pocket drug costs, they should consider strategies to increase participation in existing programs that alleviate cost burdens among low-income Medicare beneficiaries.

Keywords: Medicare Part D; diabetes mellitus; drug costs; health expenditures; older adults; out-of-pocket costs; poverty.

Publication types

  • Research Support, U.S. Gov't, P.H.S.
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Diabetes Mellitus* / drug therapy
  • Drug Costs
  • Health Expenditures
  • Humans
  • Medicare Part D*
  • Poverty
  • Prescription Drugs* / therapeutic use
  • United States


  • Prescription Drugs