Objectives: We aimed to investigate whether uncomplicated type A intramural hematoma (IMHA) patients with type 2 diabetes mellitus (DM) who underwent a "wait-and-watch strategy" and tight glycemic control had similar clinical outcomes as patients without DM who received the same treatment strategy.Methods: Between January 2010 and December 2016, uncomplicated IMHA patients with and without diabetes mellitus were included and were propensity score-matched to improve the balance between the two groups. Cox proportional hazard models were constructed to identify the specific factors associated with aorta-related mortality. The Fine-Gray model for the competing risk analysis was used to estimate the aorta-related and nonaorta-related mortality in different groups during the follow-up period.Results: A total of 109 IMHA patients were included in this study, and 66 patients were included after matching. Patients without DM experienced significantly more aorta-related adverse events (51.6% vs 13.3%; P = .001) and reinterventions than patients in the DM group (29.0% vs 6.7%; P = .023). Cox regression analysis revealed that a higher matrix metalloproteinase-9 level (hazard ratio [HR], 1.70; 95% confidence interval [CI], 1.39-2.09; P < .001) and larger maximum aortic diameter (HR, 1.41; 95% CI, 1.11-1.80; P = .005) were associated with higher aorta-related mortality. The competing risk analysis revealed a significantly higher aorta-related mortality during the follow-up period in the no DM group than in the DM group (36.4%; 95% CI, 11.6%-82.3%; P = .0294).Conclusions: Uncomplicated IMHA patients with DM (receiving the "wait-and-watch strategy" and tight glycemic control) may have lower aorta-related mortality and rates of aorta-related adverse events and reinterventions than the no DM group. [ABSTRACT FROM AUTHOR]