BACKGROUND: Long duration of diabetes mellitus (DM) is associated with an increased risk of infection, however no studies have yet focused on the duration of DM and the associated risk of infective endocarditis (IE).

METHODS: Patients with DM were identified through the Danish Prescription Registry, 1996-2015. Duration of DM was split in follow-up periods of: 0-5 years, 5-10 years, 10-15 years, and >15 years. Multivariable adjusted Poisson regression was used to calculate incidence rate ratios (IRR) according to study groups. DM late-stage complications and the associated risk of IE were investigated as time-varying covariates using the validated Diabetes Complications Severity Index (DCSI).

RESULTS: We included 299,551 patients with DM. In patients with DM duration of 0-5 years, 5-10 years, 10-15 years, and >15 years, the incidence rates of IE were 0.24, 0.33, 0.58, and 0.96 cases of IE/1000 person years, respectively. Patients with DM duration 5-10 years, 10-15 years, and >15 years were associated with a higher risk of IE with an IRR of 1.24 (95% CI: 1.02-1.51), 1.92 (95% CI: 1.52-2.43) and 3.05 (95% CI: 2.11-4.40), respectively, compared with DM duration 0-5 years. Patients with a DCSI score of 2, 3 and >3 were associated with a higher risk of IE compared with patients with a DCSI score of 0, IRR = 1.78 (95% CI: 1.34-2.36), IRR = 2.34 (95% CI: 1.73-3.16), and IRR = 2.59 (95% CI: 1.92-3.48), respectively.

CONCLUSION: This study shows a stepwise increase in the risk of IE with DM duration and severity independent of age and known comorbidity.