Impact of Diabetes Mellitus on Clinico-Radiological Manifestations and Treatment Outcomes in Drug-Sensitive Pulmonary Tuberculosis.

Tuberculosis (TB) remains one of the leading infectious causes of mortality worldwide. In recent years, the global surge in Type 2 Diabetes Mellitus (DM) has emerged as a major challenge to TB control. Individuals with DM have a two- to three-fold increased risk of developing active TB compared to those without diabetes. Furthermore, the dual burden is highly concentrated in low- and middle-income countries, with India accounting for a massive share of both diseases.

Pathophysiologically, DM disrupts early host defenses against Mycobacterium tuberculosis. Chronic hyperglycemia impairs phagocyte function, alters macrophage activation, and leads to delayed immune recalibration. These immunological shifts translate into distinct clinical outcomes. While the NTEP has successfully expanded bidirectional screening, data detailing the precise impact of varying glycemic control on specific clinico-radiological manifestations and localized treatment outcomes in endemic regions remain limited. This study aims to bridge that gap by evaluating these parameters in a tertiary care setting.

Study Design and Setting: A prospective observational study conducted at the Post Graduate Department of Respiratory Medicine, M.K.C.G. Medical College & Hospital, Berhampur, Odisha.

Study Period: August 2024 through 2026.

Ethics: Approved by the Institutional Ethics Committee, M.K.C.G. Medical College (Approval No. EC/NEW/INST/2022/2934). Written informed consent was obtained from all participants.

Inclusion Criteria: Patients diagnosed with drug-sensitive pulmonary tuberculosis treated under NTEP guidelines.

Data Collection: Patients were categorized into TB with DM (TB-DM) and TB without DM (TB-only). Clinical presentations, chest radiographs (graded for disease extent/cavitation), and sputum smear grades were recorded at baseline, end of the intensive phase (2 months), and at treatment completion.

Description: This table compares the baseline age, gender distribution, and body mass index (BMI) between the TB-DM and TB-only groups.

Table 1: Baseline Demographic and Clinical Characteristics

Significant finding: Patients in the TB-DM cohort were statistically older and had a higher baseline BMI compared to the TB-only cohort (p < 0.05).

Description: Outlines the prevalence of classic TB symptoms between the two cohorts.

Table 2: Comparison of Clinical Symptomatology at Presentation

Significant finding: Haemoptysis was observed significantly more often in the diabetic group (32% vs 12%, p < 0.01), likely reflecting a higher degree of localized tissue destruction.

Description: Details the extent of lung involvement and the presence of cavitary lesions based on initial chest X-rays.

Table 3: Radiological Manifestations at Baseline

Significant finding: The TB-DM group showed a statistically significant increase in atypical presentations, such as lower lung field involvement, as well as a higher propensity for cavitary lesions (p < 0.01).

Description: Compares the microbiological clearance rates after two months of standard anti-tubercular therapy (ATT).

Table 4: Sputum Smear Conversion at the End of the Intensive Phase (2 Months)

Significant finding: Sputum conversion was significantly delayed in the diabetic group, with 22% remaining smear-positive at the end of the intensive phase compared to only 8% in the non-diabetic group.

Description: Displays the ultimate clinical outcomes at the end of the full treatment regimen based on NTEP definitions.

Table 5: Final Treatment Outcomes Under NTEP

Significant finding: Overall treatment success was significantly lower in the TB-DM cohort. Notably, mortality and treatment failure rates were statistically higher in patients with comorbid diabetes.

The findings of this study reinforce the growing consensus that Diabetes Mellitus profoundly alters the landscape of Pulmonary Tuberculosis. Our data show that patients with TB-DM are older and present with more severe radiological destruction, notably a higher prevalence of cavitary lesions and atypical lower lung field involvement.

Immunologically, chronic hyperglycemia drives a hyper-inflammatory, dysregulated immune response. As noted by Kumar et al., TB-DM is characterized by exaggerated Th1 and Th17 responses coupled with impaired regulatory control, leading to enhanced lung tissue damage. This pathological inflammation likely explains the increased rates of hemoptysis and cavitation observed in our diabetic cohort.

Crucially, DM negatively impacted microbiological clearance. The significant delay in sputum smear conversion at two months among diabetic patients prolongs the window of infectivity and increases transmission risk in the community. Furthermore, final treatment outcomes were noticeably worse in the TB-DM group, echoing previous studies by Viswanathan et al. and Vidya Mave et al., which linked DM to higher rates of treatment failure and mortality during TB therapy.

Diabetes Mellitus exerts a detrimental impact on the clinical course of Pulmonary Tuberculosis. It is a significant risk factor for extensive, cavitary lung disease, delayed sputum conversion, and adverse treatment outcomes. Active, bidirectional screening for both conditions, coupled with aggressive glycemic control alongside standard anti-tubercular therapy, is vital to reducing morbidity, mortality, and community transmission under the NTEP.

1.       World Health Organization. (2024). Global Tuberculosis Report.

2.       Ministry of Health & Family Welfare, Government of India. (2024). India TB Report.

3.       Mave, V., et al. (2021). "Impact of diabetes mellitus on tuberculosis treatment outcomes in India." Clinical Infectious Diseases.

4.       Viswanathan, V., et al. (2012). "Effect of diabetes on treatment outcome of smear-positive pulmonary tuberculosis." The International Journal of Tuberculosis and Lung Disease.

5.       Banurekha, V. V., et al. (2014). "Treatment outcomes of tuberculosis in patients with diabetes mellitus in South India." Indian Journal of Medical Research.

6.       Ranganath, T. S., et al. (2013). "Treatment success in TB patients with and without diabetes." Journal of Tuberculosis Research.

7.       Restrepo, B. I., et al. (2008). "Tuberculosis and diabetes: a re-emerging syndemic." Microbes and Infection.

8.       Kumar, N. P., et al. (2013). "Type 2 diabetes mellitus is associated with altered CD4+ T cell responses in pulmonary tuberculosis." Immunology.

9.       Kumar, N. P., et al. (2014). "Plasma cytokine profiling in active pulmonary tuberculosis with comorbid diabetes." Cytokine.

10.    Kumar, N. P., et al. (2015). "Type 2 diabetes mellitus is associated with altered CD8 T and NK cell function in pulmonary tuberculosis." Immunology.

11.    Kumar, N. P., et al. (2016). "Longitudinal analysis of T cell responses in TB-DM comorbidity during anti-TB treatment." Journal of Infectious Diseases.

12.    Andrade, B. B., et al. (2013). "Biomarkers of inflammation and tissue remodeling in TB-DM comorbidity." European Respiratory Journal.

13.    Blanca, I., et al. (2011). "Convergence of high burden TB and DM: Global health implications." Tropical Medicine & International Health.

14.    Garcia-Elorriaga, G., et al. (2014). "Diabetes as an important risk factor for the development of TB." Infectious Disease Clinics.

15.    Lincoln, E. M., et al. (2001). "Progression of primary lesions in infectious pulmonary diseases." American Journal of Respiratory and Critical Care Medicine.