Diabetes ups mortality risk in TB patients

People diagnosed with tuberculosis (TB) face a worse prognosis if they also have untreated or complicated diabetes mellitus (DM), according to a study.

“[O]ur study confirms the deleterious effects of untreated and complicated DM on anti-TB treatment,” said lead author Dr Kyung Hoon Kim from the Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.

“It is important to screen for DM status and complications at baseline and incorporate proactive DM management,” Kim added.

In this study, Kim and colleagues identified patients with diabetes among those with pulmonary TB enrolled in the Korea Tuberculosis Cohort (KTBC) registry and the multicentre prospective cohort study of pulmonary tuberculosis (COSMOTB). Unfavourable outcomes and mortality were the primary and secondary outcomes, respectively.

Multivariable logistic regression analysis was conducted to examine the effect of DM and complicated diabetes on the outcomes. Subgroup analyses were also conducted using COSMOTB to explore the relationship between various diabetes statuses and outcomes.

Consistent with the COSMOTB data analysis, DM (adjusted odds ratio [aOR], 1.93, 95 percent confidence interval [CI], 1.64‒2.26) and complicated DM (aOR, 1.96, 95 percent CI, 1.67‒2.30) significantly predicted adverse TB outcomes in the KTBC. [Respirology 2024;29:624-632]

The subgroup analysis revealed that untreated DM at baseline was independently associated with unfavourable outcomes (aOR, 2.72, 95 percent CI, 1.26‒5.61). Similarly, prediabetes and uncontrolled diabetes correlated with unfavourable outcomes and mortality, but this did not reach statistical significance.

Comorbidities

This finding supported that of another Korean study which found that uncontrolled DM at baseline independently predicted treatment failure or death. Additionally, a Taiwanese retrospective study found patients with DM-related comorbidities to be at greater risk of unfavourable outcomes. [Thorax 2017;72:263-270; PLoS One 2015;10:e0121698]

“In our study, complicated DM was defined as poor glycaemic control or complications at initial assessment,” Kim said. “The higher incidence of unfavourable outcomes could be ascribed to a higher mortality rate due to DM-related comorbidities, such as cardiovascular disease.” [Int J Tuberc Lung Dis 2019;23:783-796]

Moreover, a higher risk of drug‒drug interactions, adverse events, and high pill burdens could make it difficult to manage the coexisting TB and DM. This may result in slow treatment response and a higher incidence of clinically or microbiologically failed cases. [Int J Tuberc Lung Dis 2019;23:783-796]

Personalized treatment

“Decisions regarding TB treatment and management of coexisting health conditions should be personalized, considering disease severity, affected organs, and treatment response,” Kim said.

TB treatment can be extended to 9 months in patients with uncontrolled diabetes due to the higher rates of recurrence, suggests another study. [Clin Infect Dis 2016;63:e147-e195]

The current study lacked evidence for extending TB treatments for those with DM since it did not assess post-treatment recurrence rates or the impact of treatment duration on outcomes. However, it showed evidence of complicated and untreated DM leading to more adverse outcomes.

“Combining stringent glucose control with prolonged anti-TB treatment might benefit these patients, but further research is essential to confirm its efficacy,” Kim said.