OBJECTIVE: To estimate associations between transportation barriers and diabetes outcomes. METHODS: Longitudinal cohort study
86 977 adults with type 2 diabetes mellitus in community-based health centers were assessed for transportation barriers, with up to 36 months of follow-up after initial assessment. We compared scenarios in which individuals did not experience transportation barriers to scenarios in which they did, to estimate differences in mean hemoglobin a1c (HbA1c), systolic and diastolic blood pressure (SBP and DBP), and LDL cholesterol. For analysis, we used targeted minimum loss estimation at the following timepoints after initial transportation barrier assessment: 12 (primary), 6, 18, 24, 30, and 36 months. The study period was June 24, 2016 to April 30, 2023. RESULTS: We estimated that if participants did not experience transportation barriers, mean HbA1c would have been 0.09% lower (95% CI = -0.14% to -0.04%, CONCLUSIONS: Absence of transportation barriers was associated with slightly lower hemoglobin A1c and blood pressure, but the small magnitude of the differences suggests that also addressing other factors may be needed to improve diabetes outcomes more meaningfully.