Background <p>Glucagon-like peptide-1 receptor agonist (GLP-1RA) treatment reduces cardiovascular events in type 2 diabetes. Yet, the impact of GLP-1RA treatment before ST-segment elevation myocardial infarction (STEMI) on long-term prognosis in patients with type 2 diabetes remains unclear. In patients with STEMI and type 2 diabetes, we aimed to investigate the association between long-term prognosis and GLP-1RA treatment before STEMI.</p> Methods <p>This nationwide cohort study included consecutive patients admitted with type 2 diabetes and STEMI in Denmark from 2010 to 2016. All data were retrieved from nationwide Danish registries. Type 2 diabetes was defined by prior hospital admission with type 2 diabetes or anti-diabetic prescriptions within one year before STEMI. Dispensed GLP-1RA medication was retrieved within one year before STEMI.</p> Results <p>Of 1421 patients with STEMI and diabetes, 7% were treated with GLP-1RA before STEMI and 93% were not. Patients treated with GLP-1RA were younger, had more comorbidities, and more often treated with other anti-diabetics. During 8.4 years, 36% patients treated with GLP-1RA died whereas 52% died in the no GLP-1RA group (<i>p</i> = 0.002). In adjusted Cox analysis, GLP-1RA was associated with lower long-term mortality (hazard ratio (HR) 0.60, 95% confidence interval (CI) 0.43–0.84). There was no association between GLP-1RA and ischemic stroke (adjusted HR 1.05, 95% CI 0.57–1.94), recurrent myocardial infarction (adjusted HR 0.74, 95% CI 0.48–1.15), or hospitalisation for heart failure (adjusted HR 0.71, 95% CI 0.48–1.05).</p> Conclusions <p>In patients with diabetes and STEMI, GLP-1RA treatment prior to STEMI admission was associated with significantly lower long-term mortality.</p>