OBJECTIVE

Type 1 diabetes is a risk factor for myocardial infarction (MI). We aimed to evaluate the case fatality in patients with type 1 diabetes after MI.

RESEARCH DESIGN AND METHODS

Consecutive patients experiencing MI with type 1 diabetes (n = 1,935; 41% female; mean age 62.5 years) and without diabetes (n = 74,671) admitted to 20 hospitals in Finland from 2005 to 2018 were studied using national registries. The outcome of interest was death within 1 year after MI. Differences between groups were balanced by multivariable adjustments and propensity score matching.

RESULTS

Case fatality was higher in patients with type 1 diabetes than in propensity score–matched controls without diabetes at 30 days (12.8% vs. 8.5%) and at 1 year (24.3% vs. 16.8%) after MI (hazard ratio 1.55; 95% CI 1.32–1.81; P < 0.0001). Patients with type 1 diabetes had poorer prognosis in subgroups of men and women and of those with and without ST-elevation MI, with and without revascularization, with and without atrial fibrillation, and with and without heart failure. The relative fatality risk in type 1 diabetes was highest in younger patients. Older age, heart failure, peripheral vascular disease, renal failure, and no revascularization were associated with worse prognosis after MI. The case fatality among patients with type 1 diabetes decreased during the study period, but outcome differences compared with patients without diabetes remained similar.

CONCLUSIONS

Patients with type 1 diabetes are at higher risk of death after MI than patients without diabetes. Our findings call for attention to vigorous cardiovascular disease prevention in patients with type 1 diabetes.