Diabetes mellitus and infective endocarditis: the insulin factor in patient morbidity and mortality

Aims To analyse the characteristics of infective endocarditis (IE) in patients with diabetes mellitus (DM), and to evaluate the prognostic significance of DM according to insulin use. Methods and results A total of 559 patients with definite IE including 75 patients (13%) with DM (insulin use n = 22; oral antidiabetic n = 53) were evaluated. Comparison of insulin-DM, oral-DM, and non-DM patients showed an older age (66 +/- 13, 66 +/- 10, 58 +/- 17, respectively; P = 0.004) in DM patients, and more frequent IE on prosthetic valves (32, 11, and 15%, respectively; P = 0.068) in insulin-DM patients. Oral streptococci (0, 8, and 18%, respectively; P = 0.016) were less frequently the causative organism than staphylococci (64, 26, and 29%, respectively; P = 0.002) in insulin-DM patients. Vegetations, dehiscence, abscess, and regurgitation rates did not differ among the three groups, nor did cardiac surgery rates (32, 47, and 48%, respectively; P = 0.334), but in-hospital mortality was higher in insulin-DM patients (50, 19, and 15%; P < 0.001). In multivariable analysis, independently of other determinants of death (age, IE location, Staphylococcus aureus, history of heart failure, immunosuppression, creatinine serum), insulin-DM was a predictor of death (OR, 4.69; 95% CI, 1.77-12.44), whereas oral-DM was not. Conclusion IE prognosis in insulin-DM patients is poor due to the coexistence of host and pathogen factors. Insulin-DM patients with IE may require specific management.