The Etiology of Lower Respiratory Tract Infections in People with Diabetes

Patients with diabetes mellitus (DM) are likely to develop many types of infections, which affect the transport of glucose into tissues. Diabetes increases the susceptibility to different kinds of respiratory infections, is often identified as an independent risk factor for developing lower respiratory tract infections. Pulmonary infections caused by Mycobacterium tuberculosis, Staphylococcus aureus, gram-negative bacteria and fungi may occur with an increased frequency, whereas infections due to Streptococcus pneumonia or influenza virus may be associated with increased morbidity and mortality. During lung infection, there are changes in the local and ciliary epithelial lining. Increased susceptibility to pneumococcal infection by people with diabetes is the result of reduced defense capability of antibodies to protein antigens. The relationship between diabetes and pulmonary tuberculosis is well known, and the incidence of tuberculosis in diabetic individuals is 4−5 times greater than among the non-diabetic population. It is thought that malfunction of monocytes in patients with diabetes may contribute to the increased susceptibility to tuberculosis and/or a worse prognosis. Hospitalization of patients with diabetes due to influenza virus or flu-like infections is up to 6 times more likely to occur compared to healthy individuals, also diabetic patients are more likely to be hospitalized due to infection complications. Immunization with influenza and anti-pneumococcal vaccines is recommended to reduce hospitalizations, deaths, and medical expenses. Diabetes, especially the uncontrolled one, predisposes to fungal infection, the most common candidiasis and mucormycosis.