Incident transient ischemic attack and subsequent cardiovascular events and mortality in patients with newly diagnosed type 2 diabetes: a population-based cohort study

Background Transient ischemic attack (TIA) is an established warning sign for stroke, but its association with broader cardiovascular outcomes during the course of newly diagnosed type 2 diabetes mellitus (T2DM) remains unclear. Methods This population-based cohort included 232,688 adults with newly diagnosed T2DM in the Xiamen Regional Healthcare Database during 2010–2025. Follow-up began at T2DM diagnosis, with hospitalized TIA modeled as a time-varying exposure. The primary outcome was a cardiovascular composite of myocardial infarction (MI), stroke, heart failure (HF), or cardiovascular mortality. Adjusted Cox models estimated hazard ratios (HRs) and 95% confidence intervals (CIs). Analyses examined exploratory subgroup interactions, age-specific absolute rates, exposure delays, smoking complete cases, and models excluding covariates with substantial missingness. Primary discharge and repeated-TIA definitions and ischemic stroke were also assessed. Results During follow-up, 11,153 participants experienced hospitalized TIA. Adjusted hazard ratios (95% confidence intervals) were 2.07 (1.96–2.20) for the cardiovascular composite, 1.98 (1.87–2.10) for all-cause mortality, 2.31 (2.09–2.55) for cardiovascular mortality, 1.55 (1.48–1.63) for HF, and 2.46 (2.32–2.61) for stroke. MI was not significantly associated with TIA (1.10; 0.99–1.22). Exploratory interactions involved age and glycated hemoglobin (HbA1c) for the composite, and sex, age, and HbA1c for stroke. Younger participants had larger relative composite and stroke associations, whereas older participants had higher unadjusted absolute event rates. Composite and stroke associations remained elevated across 7–180-day exposure delays; at 180 days, HRs were 1.69 (1.58–1.80) and 1.92 (1.79–2.06), respectively. Associations with the composite, mortality, stroke, and HF persisted across missing-data analyses and alternative TIA definitions. The ischemic stroke HR was 2.45 (2.31–2.60). Conclusion In patients with T2DM, hospitalized TIA was associated with higher subsequent hazards of the four-component cardiovascular composite, mortality, stroke, and heart failure in time-varying analyses. These findings support hospitalized TIA as a prognostic marker of broader cardiovascular risk in this population.