A Bidirectional Immunological Relationship between Diabetes Mellitus and Tuberculosis: A Narrative Review

Abstract

Tuberculosis (TB) is one of the most common contagious diseases worldwide. Over the past few decades, researchers have made significant efforts to prevent TB. Recent predictions indicate that the prevalence of Diabetes Mellitus (DM) will reach 552 million by 2023 due to ongoing epidemiological changes in several countries across the globe. India is expected to have 62-80 million people with diabetes by 2030, making it the "Diabetes Capital" of the world. Present review discusses the urgent need to understand the mechanisms and implications of DM on the immune systems of TB patients. The correlation between TB and DM has been shown to be bidirectional. Numerous studies have revealed a higher prevalence of diabetes in TB patients, as their immune systems are compromised. TB patients with DM experience progressive deficits in both innate and adaptive immune cell activity, reducing their ability to suppress Mycobacterium tuberculosis (M. tuberculosis) and increasing their risk of developing TB. Increased inflammation and elevated levels of inflammatory cytokines in circulation are characteristics of TB with DM co-morbidity, which indicate the active involvement of the angiogenesis-inflammation nexus. Therefore, to alleviate the burden of both disorders, it would be beneficial to make informed therapy choices by gaining a better understanding of TB immunology in the context of DM.