Association between Insulin use and Infective Endocarditis: An Observational Study

ABSTRACT

Abstract Background: The association between Diabetes Mellitus (DM) and Infective Endocarditis (IE) is controversial in the literature, since many controversial results have been published. However, when evaluating specifically the evidence on IE and individuals with DM using insulin, we found only two observational studies that considered this variable, with discordant results regarding the prognosis and prevalence of Staphylococcus sp in insulin users compared to non-users. Despite the lack of evidence, in clinical practice the insulin use could be interpreted as minor criteria "injection drug use", using the modified Duke criteria for IE diagnosis. Objectives: To compare the microbiological and valvar profile, as well as the outcome of non-diabetic and diabetic patients with IE who were insulin users or not. Methods: This was an observational, analytical and retrospective study of patients diagnosed with IE between 2003 and 2015 in three tertiary care centers. A total of 211 patients were included, of which 17 were diabetics and 9 were insulin users. Patients were compared using the Shapiro-Wilk normality test and Fisher's exact test, with a significance level of 5%. Results: The mortality from IE in diabetic individuals was higher than that of non-diabetic patients, but with no statistical significance (35.29% vs. 21.1%; p = 0.221), even when the groups were divided into insulin-user diabetic, non-insulin user diabetic and non-diabetic patients (33.3% vs. 37.5% vs. 21.1%, p = 0.229). There was a difference regarding the prevalence of IE caused by S. aureus (57.1% vs. 14.3% vs. 17.4%, p = 0.029) and the involvement of the tricuspid valve (33.3% vs. 0.00% vs. 10.0%, p = 0.034) among insulin users. Conclusion: In our sample, insulin use or the presence of DM did not mean higher in-hospital mortality from IE. It is not possible to generalize the microbiological and valvar findings due to the lack of studies evaluating insulin users in IE; however, particularities have been previously reported and may indicate a different behavior of IE in these patients. New studies considering the insulin use variable are required to elucidate the association between DM and IE.