Insulin Access and Health Outcomes After the Inflation Reduction Act's Out-of-Pocket Spending Caps

Due to the high cost of insulin, over 1 million individuals in the United States skip insulin doses to save money, increasing their risk of avoidable diabetes-related complications and mortality. In a landmark policy change, the Inflation Reduction Act capped out-of-pocket costs for insulin at $35 per 30-day supply for Medicare beneficiaries. Little is known about the cap’s impacts on insulin access and health outcomes for people who use insulin, including existing disparities by race/ethnicity and income. Understanding the impacts of the cap is necessary to inform future policy to ensure access to insulin and other potentially life-saving drugs for all patients.
The long-term goal is to identify policy solutions to increase the affordability of insulin for everyone and thereby reduce disparities in avoidable diabetes-related hospitalizations and mortality. The overall objective of this project is to measure the effect of the Inflation Reduction Act’s cap on insulin out-of-pocket costs on insulin access and health outcomes, including changes in disparities by race/ethnicity and income. The general hypothesis is that the Inflation Reduction Act cap improved insulin affordability, reduced insulin rationing, and improved health outcomes while reducing disparities, but may also have had unintended consequences relevant to insulin access such as higher Part D plan premiums or fewer insulins covered. The objective will be achieved via three specific aims: (1) Evaluate the impact of the Inflation Reduction Act cap on out-of-pocket costs for insulin, insulin use, glycemic control, and health care outcomes among Medicare beneficiaries; (2) Measure heterogeneity in the impact of the Inflation Reduction Act cap on out-of-pocket costs for insulin, insulin use, glycemic control, and health care outcomes by race/ethnicity and income; (3) Assess the link between the Inflation Reduction Act cap and changes in the standalone Part D plans serving insulin users, including increases in premiums, fewer insulin products covered, or plans exiting the market. Aims 1 and 2 will be achieved by comparing changes in outcomes between insulin users who were affected and unaffected by the policy using nationwide Medicare data and a large database of electronic medical records. Aim 3 will be achieved by measuring changes in the extent to which Part D plans with many insulin users increase their premiums, decrease the number of covered insulins, or exit from the Part D market.
At the successful completion of this research, the expected outcomes are the identification of mechanisms through which out-of-pocket caps impact access to insulin and health outcomes. The project is innovative in its focus and approach: Substantively, this will be the first comprehensive analysis of the Inflation Reduction Act’s cap on out-of-pocket costs for insulin including both intended and unintended consequences. Methodologically, the project includes a novel analysis of electronic health records to measure changes in clinical outcomes. These results will provide a strong basis for the future development of policy aimed at improving insulin access, which is expected to have a significant impact on avoidable diabetes-related complications.

Grant Number: 1R01DK141885-01
NIH Institute/Center: NIH
Principal Investigator: Ying Cao