Tuberculosis and Diabetes Mellitus: A Double Whammy for the Developing Nations

Abstract

With one-third of the estimated global population having tuberculosis and 10 million new cases added yearly, tuberculosis remains a persistent global public health problem requiring urgent attention. India has the highest tuberculosis burden (2.1 million new cases and 280,000 deaths annually) with the second largest diabetic population of the world. Nearly 40-50% adult population in India have tuberculosis infection; primary infection reactivates to clinical disease in 5-10% individuals, rest remaining latent. Conversion from latent to active disease is mainly due to underlying immunodeficiency states, diabetes being a pre-eminent cause. Tuberculosis and diabetes interact with each other at multiple levels. Diabetes triples the risk of tuberculosis. An estimated 15% of adult TB worldwide is attributed to diabetes. India and China together account for >40% of all diabetes associated tuberculosis cases; diabetes accounts for 14.8% of overall pulmonary and 20.2% smear-positive tuberculosis. Diabetic tuberculosis patients on anti-tubercular treatment (ATT) remain contagious longer than non-diabetics on ATT. Tuberculosis itself can lead to impaired glucose tolerance and overt diabetes. Moreover, certain anti-tubercular drugs interact with oral anti-diabetics, making diabetes control difficult. Development of universal, cost effective bi-directional screening methods for tuberculosis in diabetics and vice-versa could improve outcome of both diseases. However, universal screening for diabetes alone is not feasible in developing nations; additional screening for tuberculosis or bi-directional screening would be an extra burden. Certain measures, based on context of local health systems and availability of resources can be adopted: (i) tuberculosis surveillance among diabetics in regions with medium to high tuberculosis burden; (ii) assessing cost-effectiveness of universal tuberculosis screening in all diabetics; (iii) establishing dedicated referral system for diabetics with suspected tuberculosis to specialized centers; (iv) screening tuberculosis patients for diabetes at the start of ATT; (v) research in developing more effective treatment strategies for concurrent tuberculosis and diabetes.