# Natural Experiments of the Impact of Population-targeted Policies to Prevent Type 2 Diabetes and Diabetes Complications - 2020 > **NIH ALLCDC U18** · DUKE UNIVERSITY · 2024 · $457,508 ## Abstract PROJECT SUMMARY/ABSTRACT This project seeks to determine whether 3 natural experiments that reduce out-of-pocket costs for diabetes patients improve acute and chronic diabetes complications over the longer term. These natural experiments include: (1) employer adoption of preventive drug lists (PDLs) that make diabetes-related medications $0, (2) state legislation capping patient out-of-pocket costs for insulin, and (3) employer transitions from high- deductible health plans (HDHPs) with substantial financial barriers for most services to generous low- deductible plans. Results could provide evidence about actionable interventions at multiple levels that improve the health of diabetes patients. Studies will leverage a large, national health insurance claims database from 2007-2023 that the research team has refined under previous projects. The Specific Aims of the project are to: 1. Assess 15-year national trends in (a) diabetes complications and (b) uptake of federal, state, and employer natural experiments of interest. Analyses will assess 2009-2023 trends in acute preventable and chronic microvascular and macrovascular complications, including stratification by key subgroups of interest. Measures related to natural experiment uptake will comprise annual PDL adoption, state-level insulin cost trends, and HDHP to low-deductible plan switches. These analyses will use a longitudinal, calendar time series design with joinpoints, adjusted for changing demographics, socio-economic status, and co-morbidity. 2. Determine if reducing drug out-of-pocket costs improves diabetes complications. Over 4 follow-up years, Aim 2a will examine whether employer switches from health savings account (HSA)-HDHPs with high drug out-of-pocket costs to PDL HSA-HDHPs with $0 preventive drugs reduce acute and chronic diabetes complications. Aim 2b will assess these outcomes before and after approximately 10 US states limit insulin cost sharing. Analyses will use a highly rigorous interrupted time series with control series study design and Aim 2a will also apply a segmented survival with control group design. 3. Determine if reducing outpatient and emergency department out-of-pocket costs improves diabetes complications. Analyses will assess if switching from HDHPs with high cost sharing for outpatient and emergency department care to generous low-deductible plans reduces the risk of acute and chronic diabetes complications over 4 follow-up years. This aim will also use rigorous controlled interrupted time series and segmented survival designs. 4. Examine the long-term impact of reduced out-of-pocket costs on key diabetes subgroups including low-income and high-morbidity members. Aim 4 will involve stratifying Aims 2 and 3 analyses by characteristics such as income, morbidity, race/ethnicity, and diabetes severity. This aim will use the same study designs as for Aims 2 and 3 but stratified by the factors of interest. ## Key facts - **NIH application ID:** 10854715 - **Project number:** 5U18DP006696-04 - **Recipient organization:** DUKE UNIVERSITY - **Principal Investigator:** James Franklin Wharam - **Activity code:** U18 (R01, R21, SBIR, etc.) - **Funding institute:** ALLCDC - **Fiscal year:** 2024 - **Award amount:** $457,508 - **Award type:** 5 - **Project period:** 2021-10-04 → 2025-09-29 ## Primary source NIH RePORTER: https://reporter.nih.gov/project-details/10854715 ## Citation > US National Institutes of Health, RePORTER application 10854715, Natural Experiments of the Impact of Population-targeted Policies to Prevent Type 2 Diabetes and Diabetes Complications - 2020 (5U18DP006696-04). Retrieved via AI Analytics 2026-06-02 from https://api.ai-analytics.org/grant/nih/10854715. Licensed CC0. --- *[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*