Who
The study included 110 adult patients with type 2 diabetes mellitus (T2DM) treated at Adam Malik Hospital, Medan, consisting of:
- 55 cases: T2DM patients with pulmonary TB
- 55 controls: T2DM patients without pulmonary TB
Eligibility criteria:
- age ≥18 years
- physician-diagnosed type 2 DM
- complete medical record data
Exclusion criteria:
- extrapulmonary TB
- incomplete clinical documentation
Case definition:
- pulmonary TB confirmed by GeneXpert MTB/RIF
Control definition:
- T2DM patients with no history of pulmonary TB, based on medical records
Reported characteristics:
- In cases, the largest subgroup was age 45–54 years (50.9%), male (62.1%), senior high school educated (54.0%), unemployed (59.6%), smokers (69.0%), and underweight (56.4%)
- In controls, the largest subgroup was age 45–54 years (38.2%), female (68.2%), junior high school educated (66.7%), employed (60.4%), smokers (84.6%), and underweight (34.5%)
Important caution: the case and control groups appear imbalanced on several baseline characteristics, which complicates interpretation of reported odds ratios.
What
The study aimed to identify factors associated with pulmonary TB among patients with type 2 DM.
Outcome variable
- Presence or absence of pulmonary TB
Independent variables
- age
- sex
- education level
- employment status
- body mass index (BMI)
- smoking history
- HbA1c level
HbA1c classification
- controlled: <7.0%
- uncontrolled: ≥7.0%
Main findings
Bivariate analysis showed significant associations between pulmonary TB and:
- age <55 years: OR 4.741; 95% CI 2.099–10.710
- male sex: OR 3.514; 95% CI 1.569–7.869
- unemployment: OR 2.253; 95% CI 1.050–4.834
- smoking: OR 12.250; 95% CI 4.485–33.460
- abnormal BMI: OR 4.225; 95% CI 1.905–9.371
- low education: OR 3.148; 95% CI 1.430–6.931
A separate table reportedly showed that:
- HbA1c >7% was associated with an approximately 11-fold higher risk of pulmonary TB compared with HbA1c ≤7%
In multivariable logistic regression:
- smoking remained a significant factor and had the strongest adjusted association with pulmonary TB among T2DM patients (p < 0.001)
Authors’ interpretation: smoking was the dominant risk factor for pulmonary TB in patients with T2DM.
Careful interpretation: this study supports an association, not causation. The very large ORs for smoking and HbA1c should be interpreted cautiously given the apparent imbalance between groups and incomplete reporting of the adjusted model.
When
The study was conducted from January to June 2024.
Where
The study took place at Adam Malik Hospital, Medan, Indonesia, using hospital medical record data.
Why
The study sought to address which patient-related factors are associated with the occurrence of pulmonary TB in people with type 2 DM, a clinically important question because diabetes may increase TB susceptibility and worsen outcomes.
How
This was an observational analytical study using a case-control design.
Methods:
- 1:1 case-control ratio
- non-probability consecutive sampling
- hospital-based recruitment from medical records
- pulmonary TB diagnosis confirmed with GeneXpert MTB/RIF
- factors assessed from clinical and demographic data
Statistical approach:
- chi-square test for bivariate analysis
- logistic regression for multivariable analysis
Strength of evidence
This is a hospital-based case-control study, which provides moderate observational evidence for association but is limited for causal inference. It is stronger than a purely descriptive study, but still vulnerable to selection bias, confounding, and measurement limitations.
Major limitations and interpretation issues
-
Case and control groups may not be comparable
The groups appear substantially different by sex, employment, education, BMI, and possibly smoking distribution. This raises concern for confounding and unstable effect estimates. -
Very large odds ratios need caution
The reported ORs for smoking and HbA1c >7% are large and may partly reflect residual confounding, selection issues, or model instability. -
Sampling method may introduce bias
Consecutive non-probability sampling limits representativeness and may affect internal validity. -
Hospital-based design
Findings may not generalize well to all T2DM patients in the community. -
Control selection details are limited
Controls were defined by absence of pulmonary TB history in records, but the text does not clarify whether they were systematically screened to exclude undiagnosed TB. -
Inconsistency in table presentation
Table 1 reportedly mixes column percentages and row percentages, making interpretation less transparent.
Overall concise interpretation
This case-control study of 110 T2DM patients at Adam Malik Hospital found that younger age (<55 years), male sex, unemployment, low education, abnormal BMI, smoking, and HbA1c >7% were associated with pulmonary TB in bivariate analyses. In multivariable analysis, smoking remained the most important associated factor. However, the findings should be interpreted carefully because the case and control groups appear imbalanced, some reported effect sizes are very large, and the adjusted model is not fully presented.
Source: Harahap K, Sinaga BY, Syarani F, Eyanoer PC. Factors Associated with the Incidence of Pulmonary Tuberculosis in Patients with Type 2 Diabetes Mellitus. Mutiara Medika: Jurnal Kedokteran dan Kesehatan. 2025 Jul 31;25(2):123-31.