Diabetes and TB: Why Screening Could Save Lives
"Discover how a simple, two-way screening process can improve detection and outcomes for both diabetes and tuberculosis, especially in high-risk regions."
Tuberculosis (TB) and diabetes mellitus (DM) are two significant global health challenges, often coexisting and exacerbating each other. India, bearing a substantial burden of both diseases, faces unique challenges in managing their combined impact. Individuals with diabetes are more susceptible to TB, and TB can worsen glycemic control in those with diabetes, creating a dangerous cycle.
Recognizing this interconnectedness, healthcare professionals are advocating for bidirectional screening programs. This involves screening TB patients for diabetes and diabetes patients for TB. The goal is early detection and management of both conditions, ultimately improving patient outcomes and reducing the overall disease burden.
This article explores the rationale behind bidirectional screening, its implementation, challenges, and potential benefits, particularly in high-risk populations like those in India. By understanding the importance of this integrated approach, we can take proactive steps towards better health management and disease prevention.
The Diabetes-TB Burden
Diabetes is common among people with tuberculosis. A 2026 review reported an overall diabetes prevalence of 16.2% among tuberculosis patients, while a 2019 analysis of 200 studies involving 2,291,571 people with active tuberculosis found a pooled prevalence of 15.3%. Screening coverage remains incomplete: in 2020, 22 countries reported testing 47,041 people newly diagnosed with TB for diabetes, with a median testing coverage of 55%.
Current Screening Methods
For TB screening among people with diabetes, the primary approach involves asking about symptoms and using chest X-ray detection. People with abnormal chest X-ray findings or symptoms may then undergo further evaluation. For diabetes screening, WHO recommends biochemical testing for adults with diabetes symptoms and for adults aged 40 years or older with a BMI above 25 kg/m2. These approaches are useful but are informed by evidence that includes observational studies and lacks some types of stronger comparative evidence.
Two Long Medical Histories
Descriptions of diabetes date back to the Ebers papyrus, dated to approximately 1500 BC, and clinical signs were also described by ancient Egyptian, Indian, Chinese, and Arab physicians. A major TB milestone occurred on March 24, 1882, when Dr. Robert Koch announced the discovery of Mycobacterium tuberculosis, the germ that causes TB. Diabetes care also developed through milestones associated with Joslin, including Dr. Joslin's first diabetes survey in 1898.
The Double Threat: Why Screening Matters
The synergistic relationship between TB and diabetes creates a concerning global health issue. The World Health Organization (WHO) and the International Union Against Tuberculosis and Lung Disease emphasize the necessity of international guidelines for the combined management of these diseases. Studies have shown that people with diabetes have a threefold higher risk of developing active TB.
- Study Design: A prospective observational study was conducted at a Diabetes Centre and Pulmonary Medicine Department.
- Participants: The study included TB patients and diabetes patients over the age of 15.
- Screening Process: TB patients were screened for diabetes using random blood glucose (RBG) tests, followed by fasting blood glucose (FBG) tests if necessary. Diabetes patients were screened for TB based on symptoms like persistent cough, fever, and weight loss.
- Treatment: Patients diagnosed with either TB or diabetes received appropriate treatment according to national guidelines.
Evidence Supporting Rigorous Screening
Recent research emphasizes the need for rigorous screening because diabetes is associated with an increased risk of TB. The WHO TB Knowledge Sharing resource notes that evidence is limited on the optimal timing and frequency of screening among people living with diabetes, although studies suggest that glycaemic status may matter. A 2025 review similarly argues that screening can support earlier detection and potentially reduce TB transmission, morbidity, and mortality.
Worse Outcomes With Comorbidity
The available evidence identifies important failures when diabetes and TB occur together. Endotext reports that diabetes increases the risks of TB treatment failure, death, and relapse, while noting that these risks may be underestimated because of loss to follow-up or unreported outcomes. A systematic review and meta-analysis reports that diabetes nearly doubles mortality risk and increases treatment failure and relapse. These findings show why identifying and managing the comorbidity is clinically important.
What Screening Studies Measure
The 2026 diabetes-screening review focused on studies measuring the yield and prevalence of diabetes identified through diabetes screening among people with TB. Its inclusion criteria required TB to be identified microbiologically. This provides a defined basis for comparing screening yields across studies, although the available source material does not provide a comparative result for different screening strategies.
Looking Ahead: Towards Integrated Care
The study's success underscores the feasibility of integrating bidirectional screening into routine healthcare. By leveraging existing healthcare infrastructure and training healthcare workers, we can significantly improve early detection rates for both TB and diabetes. This is particularly important in resource-limited settings where access to specialized care may be challenging.
Why Screening Matters
A 2026 review found that the overall pooled yield of diabetes screening among people with TB was 7.8%, with a reported range from 2.6% in the Western region to higher values elsewhere. WHO reports that diabetes is associated with about twice the risk of TB disease and with a higher risk of multidrug-resistant TB. A cost-effectiveness analysis also concluded that screening older diabetic patients for latent TB infection is cost-effective, while emphasizing that economic considerations should shape the strategy.
Refining HbA1c Screening
Emerging research suggests that HbA1c interpretation may need to account for the course of TB treatment. One study reported that HbA1c levels declined with anti-tuberculosis treatment. It concluded that repeating HbA1c testing when treatment is completed could reduce the risk of misdiagnosing diabetes. Research from India has also examined how diabetes growth may affect tuberculosis trends.
A Shared Public Health Challenge
The comorbidity of diabetes and TB is described as a major public health challenge. A narrative review reports that people with diabetes have impaired immune function, which can make it harder to respond to infection. Public-facing health information likewise states that people living with diabetes face a higher risk of developing TB because diabetes can make it harder for the body to fight infection. These linked vulnerabilities make coordinated screening and care important system-level concerns.
Consequences for Patients
For patients with TB, diabetes is associated with higher risks of treatment failure, death, and relapse. A study by Baker and colleagues reported increased risks of failure and death combined, death alone, and relapse among patients with tuberculosis who had diabetes. More recent reviews have reconfirmed that diabetes is associated with an increased risk of developing TB. These outcomes explain why recognizing the connection is more than a statistical exercise: it can affect whether treatment succeeds and whether disease returns.
While the study demonstrates the potential of bidirectional screening, it also highlights some challenges. These include ensuring patient follow-up for further testing and treatment, coordinating care between different healthcare providers, and maintaining accurate records. Addressing these challenges requires a multi-faceted approach involving healthcare providers, policymakers, and community organizations.
Ultimately, bidirectional screening represents a crucial step towards integrated care for TB and diabetes. By recognizing the interconnectedness of these diseases and implementing proactive screening programs, we can improve patient outcomes, reduce the burden on healthcare systems, and create healthier communities.