Background: Diabetes mellitus (DM) is an important risk factor for adverse outcomes following acute myocardial infarction (AMI), but large-scale studies investigating the differential impact of Type 1 DM (T1DM) and Type 2 DM (T2DM) on AMI outcomes are lacking. Methods: All adult discharges for AMI in the National Inpatient Sample (October 2015 to December 2018) were included and stratified into T1DM, T2DM and non-DM (NDM) groups. Outcomes of interests were all-cause mortality, major adverse cardiovascular and cerebrovascular events (MACCE), major bleeding and acute ischemic stroke, as well as invasive management. Binomial hierarchical multilevel multivariable logistic regression with adjusted odds ratios (aOR) and 95 % confidence intervals (95 % CI) was used to investigate the association between DM and its subtypes with the AMI outcomes. Results: Out of 2,587,615 patients, there were 29,250 (1.1 %) T1DM and 1,032,925 (39.9 %) T2DM patients. After multivariable adjustment, patients with T1DM had increased odds of MACCE (aOR 1.20, 95 % CI 1.09–1.31), all-cause mortality (aOR 1.20, 95 % CI 1.08–1.33) and major bleeding (aOR 1.28, 95 % CI 1.13–1.44), whilst T2DM patients had increased odds of MACCE (aOR 1.03, 95 % CI 1.01–1.05) and ischemic stroke (aOR 1.09, 95 % CI 1.05–1.13), compared to NDM patients. The adjusted odds of receiving percutaneous coronary intervention were lower in both T1DM and T2DM patients (aOR 0.70, 95 % CI 0.66–0.75 and aOR 0.95, 95 % CI 0.94–0.96, respectively), but T2DM patients showed higher utilization of composite percutaneous and surgical revascularization (aOR 1.03, 95 % CI 1.03–1.04) compared to NDM patients. Conclusions: DM patients presenting with AMI have worse in-hospital clinical outcomes compared to NDM patients. There are important DM type-related differences with T1DM patients having overall worse outcomes and receiving less overall revascularization.