Background: Diabetes mellitus (DM) is considered a marker of poor prognosis after cardiac surgery. We sought to investigate the effect of DM on clinical outcomes and quality of life (QoL) after transcatheter aortic valve implantation (TAVI). Methods: A total of 148 consecutive patients with symptomatic, severe aortic stenosis who underwent TAVI were included. Baseline characteristics, procedural and long-term clinical outcomes, and the results of frailty and QoL assessment with EQ-5D-3L questionnaire were compared between patients with and without DM. Results: DM was present in 48 of 148 (32.4%) patients. No differences in periprocedural risk (Logistic Euroscore and Society of Thoracic Surgeons (STS) scale) between groups were observed. There were no differences in 30-day and 12-month all-cause mortality between groups [DM( ) vs. DM(þ): 7 (7.0%) vs. 5 (10.4%), p Z 0.53 and 12 (12.0%) vs. 10 (20.8%), p Z 0.16, respectively]. No influence of DM presence on the risk of death was confirmed after adjustment for age and gender (for 30-day mortality, age/gender-adjusted OR 1.55, 95%CI 0.47 e5.17; for 12-month mortality, age/gender-adjusted OR 2.05, 95%CI 0.79e5.32). Similarly, at the longest available follow-up, mortality did not differ between groups [14 (29.2%) vs. 19 (19.0%), p Z 0.16; age/gender-adjusted OR 1.81, 95%CI 0.80e4.08]. Similar rates of other complications after TAVI were noted. Frailty measured with the 5-meter walking test was more frequently reported in patients with DM [11 (22.9%) vs. 10 (10.0%), p Z 0.035]. No differences in QoL parameters at baseline and 12 months were noted. Conclusions: Patients with DM undergoing TAVI demonstrated similar mortality, complication rates, and QoL outcomes compared to patients without DM