TB trends and the End-TB strategy
In addition to the 10 million people who suffer from TB disease each year, it is estimated that one quarter of the world’s population have latent TB infection (LTBI). Of those, 5-10% will develop TB at some stage in their lifetime. It is now recognized that the vast global reservoir of LTBI needs to be addressed in order to reach the targets of the ‘End TB strategy’: to reduce the number of TB deaths by 95% and to reduce the TB incidence by 90% by the year 2035 (compared to 2015). Child contacts of a TB patient and people living with HIV are two high-risk groups that are already targeted for preventive treatment of LTBI. However, they account for a very small proportion of the global LTBI reservoir. An obvious next step is to target other high-risk groups. One such group is people with DM in TB-endemic countries.
Increased risk of TB in people living with DM
One in eleven adults are living with DM, resulting in 463 million people worldwide. In addition, it is estimated that one in two adults with DM are still undiagnosed. Of all DM patients, 75% are living in low- and middle-income countries (LMIC), and the African region shows the fastest increase in DM prevalence in the world (+143% from 2019 to 2045). It is estimated that by 2045 there will be 47 million people living with DM in Africa. It has been shown that people with DM have a 2-3 times higher risk of developing active TB, compared to people without DM. They also suffer from more and more severe symptoms, resulting in higher rates of death, treatment failure and disease relapse. At the same time, while glycaemic control is the core treatment target for DM, TB provokes a difficult to control hyperglycaemia.
Preventive treatment of LTBI
In previous studies, we found that the increased TB risk in DM patients lies mostly in the development from latent infection to active disease, rather than in a higher risk of becoming infected in the first place. In an Indonesian population living with DM, the prevalence of LTBI was lower than in household contacts of a TB patient, but their risk to develop TB disease was 2-3 times higher. This suggests that preventive treatment of people living with DM who are LTBI positive may be beneficial. A modelling study has shown that such an approach may result in a 7-11% reduction in TB incidence, and an 8-13% reduction in TB deaths, depending on the achieved percentage of treatment coverage.
Guideline for treatment of DM-TB
In 2019, the first treatment guideline for the co-management of DM and TB has been published. The guide has been developed by The Union Against Tuberculosis and Lung Disease (The Union) in collaboration with the World Diabetes Foundation (WDF), with two of the PROTID consortium members as co-authors. The document provides very practical guidance for frontline health workers who are responsible for the diagnosis and treatment of patients with TB and DM. Starting with the management of both diseases separately, it continues to provide guidance on how to screen for TB in DM patients and vice versa, how to manage DM during TB treatment and how to manage TB in people with DM, including advice on the prevention of TB infection in DM clinics.