6.8 Diabetes and infection

6.8 Diabetes and infection^16,17

There is increased risk of infection in persons with diabetes. However, infection may worsen diabetes control. Hyperglycemia impairs humoral immunity and leukocyte functions. Persons with long-standing diabetes tend to have vasculopathy with resultant poor tissue perfusion. Moreover, diabetic neuropathy results in unnoticed injury – all of which can precipitate infection.
The most common sites of infection in diabetes are the skin and urinary tract. Spread of infection bone causing osteomyelitis is common in diabetes. Lower urinary tract infections and acute pyelonephritis are seen with greater frequency.
A few infections, such as malignant otitis externa, rhinocerebral mucormycosis, emphysematous pyelonephritis and emphysematous cholecystitis occur almost exclusively in persons with diabetes. Infection at insulin injection site, sometimes leading to abscess formation, though not common, may add to the suffering of the person. Some antidiabetic drugs may precipitate infection – SGLT2 inhibitors can precipitate UTI and genital fungal infection; DPP4 inhibitors, GLP1 receptor agonists and thiazolidinediones can precipitate nasopharyngeal infections.
Management of hyperglycemia is crucial not only to contain the infection, but also to prevent fatal acute complications of diabetes. Insulin is the best option to control diabetes in presence of infection. In case of very minor infection non-insulin agents may be continued with cautious supervision. At the same time aggressive management of the particular infection with appropriate antibiotic should be ensured.

6.8.1 Tuberculosis

6.8.1 Tuberculosis¹⁸

Subjects with diabetes are three to five times at higher risk of getting active tuberculosis compared to those without diabetes. Often they do not have classical features, are associated with increased morbidity, drug resistance and relapse. On the other hand, tuberculosis can cause glucose intolerance and lead to increased incidence of diabetes mellitus. Insulin is the best option, specially during early phase, severe infection (like disseminated or military TB, tubercular meningitis), lean and thin patients, while using steroid etc. Moreover, some anti-TB drugs have interaction with some OADs.

6.8.2 COVID-19

6.8.2 COVID-19¹⁹

People with diabetes have increased risk of getting more severe form of COVID-19, though there is no sufficient proof of increased incidence of, or death from, the disease. There is increased risk of diabetes in individuals who have suffered from COVID-19. For control of blood glucose insulin is the best choice in case of moderate to severe disease. For critically ill COVID-19 patients, specific protocol should be followed for glycemic control. For mild cases noninsulin agents may be used with close monitoring.