Abstract:

Background: Tuberculosis (TB) remains to be one of the infectious diseases of global concern caused by a bacteria called Mycobacterium tuberculosis usually attacking the lungs and can also attack some other parts of the body. Not everyone infected with TB bacterium becomes sick, as a result of this, two TB-related conditions exist namely Latent TB infection (LTBI) and TB disease., About one-quarter of the population worldwide is latently infected (World Health Organization, 2021c). In addition, WHO in 2020 estimated about 10 million people developed active TB and 1.5 million people died worldwide thus indicating that if the TB disease is not treated properly can be fatal It is also known that, the largest TB risk is among individuals with a compromised immune system (Diabetes, HIV, malnutrition, or ageing). There is clinical evidence pointing to a higher prevalence of infectious diseases including TB among individuals with type 2 Diabetes (DM) which continues to gain global dominance. Reported data are showing association between active TB and glucose intolerance. It is not known with certainty whether Latent tuberculosis infection (LTBI) may increase the risk of glucose intolerance due to inability to characterize the direction of relationship between LTBI and glucose intolerance. Hence, this study aimed at having a better understanding of the trajectory link of Latent TB infection and glucose intolerance among adults in Mwanza city.

Objectives: The study aimed at determining the prevalence of glucose intolerance among adult TB case contacts in Mwanza city as well as the association between LTB infection and other risk factors for glucose intolerance among adult TB case contacts in Mwanza city.

Methods: This study used retrospective cohort study design, nested within Chronic Infections, Co-morbidities and Diabetes in Africa (CICADA) cohort and recruited participants who were resident of Ilemela and Nyamagana districts who previously participated in Nutrition, Diabetes and Pulmonary Tuberculosis (TB-NUT), conducted from 2006 to 2009 and were invited to join CICADA, a cohort study that was investigating the burden of and risk factors for diabetes in Mwanza, Tanzania, from 2016 to 2020. The study used secondary data to link the association between LTBI and glucose intolerance.

Results: A total of 194 neighbours (NB) and households (HH) of the TB case index were recruited and enrolled in this cohort from April 2006 to December 2009 and followed up for the development of glucose intolerance (pre-diabetes and diabetes) over a period of almost 10 years. Of these 194 participants, 113 (58.2%) of the NH and HH showed up at the end of 2016 – 2020 for glucose intolerance examinations, of which 54 (47.8%) were LTBI negative and 59 (52.2%) positive at the time of baseline recruitment as tested by QFT. Factors that marginally associated with development of prediabetes and diabetes in a span of 10 years were: female gender (OR 5.3, [95% CI 0.84; 36.1], P = 0.07), having higher education (OR 0.18, [95% CI 0.02; 1.24], P = 0.08), and free fat mass index (Kg) (OR 1.39, [95% CI 0.96; 2.01], P = 0.07). Those with latent TB infection were 2.7 times more likely to develop pre-diabetes or diabetes (OR 2.7, [95% CI 1.00; 7.39], p = 0.05), and those with a body mass index> 25kg/m2 were 6.2 times more likely to develop prediabetes and diabetes (OR 6.23, [95% CI 0.98; 39.4], p = 0.05).

Conclusion: This study provides valuable insights and understanding of the potential links between latent TB infection and glucose intolerance among adults in Mwanza City, Tanzania, paving the way for future research and the need for continued investigation into the complex interplay between infectious diseases and metabolic health that could shape clinical practice and public health strategies in the quest for improved health outcomes.

Key words: Latent Tuberculosis Infection, Glucose intolerance, Mwanza city, Northern Tanzania