BackgroundAlthough diabetes mellitus (DM) increases the incidence of infective endocarditis (IE), little is known about the outcome of valve surgery for active IE in patients with DM. We evaluated the clinical outcomes of valve surgery for IE in patients with DM. MethodsBetween 2009 and 2016, 470 patients underwent valve surgery for definitive left-sided active IE at 12 affiliated hospitals. We compared the preoperative variables and clinical outcomes between patients without (n = 374) and with DM (n = 96). ResultsStaphylococcus and chronic hemodialysis were more prevalent in patients with DM, and these patients had greater preoperative inflammation levels and worse renal function than patients without DM. In-hospital mortality was 8% in patients without DM and 13% in patients with DM (P = .187). The overall survival rate at 1 and 5 years was 87% and 81% in patients without DM and 72% and 59% in patients with DM (P < .001). The incidence of infection-related death was greater in patients with DM than in patients without DM (P < .001; hazard ratio 3.74 [1.78-7.71]). Freedom from the recurrence of endocarditis at 1 and 5 years postoperatively was 98% and 95% in patients without DM, and 89% and 78% in patients with DM (P < .001), respectively. The Cox hazard analysis revealed that the presence of DM was the only independent risk for recurrence (hazard ratio 3.74 [1.45-9.54], P = .007). ConclusionsThe short- and mid-term outcome after valve surgery for active IE in patients with DM is worse because of the greater prevalence of infection-related death and IE recurrence.