Long-Term Effects of a Diabetes Disease Management Program on Quality of Care and Costs: A Staggered Difference-in-Differences Analysis

Abstract Background & Aim: Evidence on long-term effectiveness of diabetes disease management programs (DMPs) remains limited, with mixed findings on sustainability and cost-effectiveness. This study evaluates the long-term impact of a comprehensive DMP on quality of care and healthcare costs over six years (2018–2023). The DMP was implemented in 17 Swiss primary care practices and featured guideline-based individualized treatment plans, continuous process evaluation, interprofessional collaboration, and quality circles. We assessed the program's impact on guideline-adherent diabetes care, hospitalization, and healthcare costs over six years (2018–2023). Methods: A staggered difference-in-differences (DiD) design analyzed claims data from 2,813 patients in 17 DMP practices (treatment group) and 17,906 patients receiving usual care (control group). Outcomes included guideline-adherent diabetes care (HbA₁c monitoring, lipid profiling, nephropathy assessment, ophthalmological examination), hospitalization, and healthcare costs. The staggered DiD approach accounted for variations in implementation timing and controlled for patient- and year-fixed effects. Results: Patients in DMP practices showed a sustained 6 to 11 percentage point improvement in guideline-adherent diabetes care (95% CI for the fifth follow-up year: 8 to 14 percentage points) compared to controls. Hospitalization rates did not differ significantly between groups (95% CI for the fifth year: -0.05 to 0.00). Healthcare cost growth was significantly lower in the DMP group in years three (95% CI: CHF -2353 to -879), four (95% CI: CHF -3023 to -1419), and five (95% CI: CHF -2942 to -796), representing average cost savings exceeding 10% of total healthcare costs per patient. Conclusion: The DMP led to sustained improvements in guideline-adherent diabetes care and reduced healthcare cost growth over six years. The staggered DiD design provides robust evidence across diverse settings and implementation timelines, addressing key gaps in long-term DMP effectiveness research. These findings support broader implementation of structured DMPs for improving quality and efficiency of diabetes care in primary care settings.