Background-Patients with diabetes mellitus (DM) are at high risk for mortality after myocardial infarction (MI). Despite an overall trend of reduced mortality after MI, the mortality gap between MI patients with and without DM did not decrease over time in previous analyses. We assessed recent trends in hospital mortality for patients with MI according to DM status. Methods and Results-We analyzed data from the National Registry of Myocardial Infarction, a contemporary registry of MI patients treated in 1964 hospitals, representing approximately one fourth of all US acute care hospitals. The study comprised 1 734 431 MI patients enrolled from 1994 to 2006, including 502 315 (29%) with DM. Crude hospital mortality decreased in all patients between 1994 and 2006 but remained higher in patients with DM compared with those without DM throughout the study. The absolute difference in mortality between patients with and without DM significantly narrowed over time, from 15.6% versus 11.5% in 1994 to 8.0% versus 6.8% in 2006 (P<0.001 for DM × time interaction). The adjusted odds ratio for mortality associated with DM declined from 1.24 (95% confidence interval, 1.16-1.32) in 1994 to 1.08 (95% confidence interval, 0.99-1.19) in 2006 (P<0.001 for trend). The largest improvement in hospital mortality was observed in diabetic women (17.9% in 1994 versus 8.4% in 2006; P<0.001). Conclusions-The hospital mortality gap between MI patients with and without DM narrowed significantly from 1994 to 2006, with the greatest improvement observed in women with DM. © 2012 American Heart Association, Inc.