Diabetes mellitus complications and their association with patient-reported outcome measures: a longitudinal study of the SwissDiab cohort

BACKGROUND: Diabetes mellitus leads to microvascular and macrovascular complications that significantly impact quality of life. Previous cross-sectional studies may overestimate complication impacts due to methodological limitations. We performed a longitudinal study to assess within-patient associations between diabetes complication severity and quality of life in type 1 and 2 diabetes, providing contemporary utility estimates for cost-effectiveness analyses. METHODS: This longitudinal cohort study used Swiss diabetes registry data (2015-2022). Patients with type 1 and 2 diabetes completing ≥2 annual EQ-5D-3L questionnaires were included. We used the adapted Diabetes Complications Severity Index (aDCSI) to quantify complication severity. Associations were examined using mixed-effects regression models, adjusted for patient characteristics and survey time. RESULTS: Among 896 participants (422 type 1, 474 type 2), 83% had ≥1 complication at baseline. Type 1 patients reported better quality of life than type 2 (EQ-5D: 0.96 vs 0.88; VAS: 82.1 vs 75.5). Higher aDCSI scores were associated with reduced quality of life in both diabetes types. Women and insulin-treated patients reported lower scores. Only 4.9% developed complications. No quality of life decrement over time was observed. CONCLUSION: Diabetes complications reduce quality of life, with myocardial infarction (-0.05 EQ-5D utility) in type 2 and renal failure (-19 VAS points) in type 1, with decrements smaller than previous estimates.