Relationship Between Glycemic Control And Ct-Based Severity Of Pulmonary Tuberculosis In Diabetics And Non-Diabetics

Abstract

Tuberculosis (TB) remains a leading infectious killer worldwide. Diabetes mellitus (DM) is a rapidly growing metabolic epidemic. By weakening the body's immune system, diabetes enables TB to spread more aggressively and destroy lung tissue. Poor blood sugar control (HbA1c ≥7%) leads to even higher CT severity scores and greater cavity burden, highlighting the need for combined TB diabetes care. DM impairs immunity, leading to extensive pulmonary TB, and poor glycemic control correlates with severe CT findings including cavitation, consolidation, and lymphadenopathy.

Aim of the Study:

The main aim of this study is to evaluate the relationship between glycemic control and CT- based severity of pulmonary tuberculosis in diabetic and non-diabetic patients, and to determine whether elevated HbA1c levels are associated with increased radiological severity.

Methodology:

This cross-sectional analytical study was carried out at Nawaz Sharif Hospital, Lahore, and included 113 patients with pulmonary tuberculosis. Each participant underwent a contrast‑enhanced chest CT examination using a 16‑slice Toshiba scanner. Based on clinical history and HbA1c measurements, participants were separated into two main groups: diabetic (47 individuals) and non‑diabetic (66 individuals). Non‑diabetic status was defined as HbA1c below 5.7%. Diabetic subjects were then subdivided according to their level of glycemic control: good control (HbA1c between 5.7% and 7%, 8 patients) and poor control (HbA1c between 7% and 10%, 38 patients). A standardized scoring system (ranging from 0 to 20 points) was used to quantify CT severity, taking into account cavity count, cavity diameter, lobar distribution, bilateral involvement, tree‑in‑bud sign, consolidation, mediastinal lymphadenopathy, pleural effusion, and bronchiectasis. Statistical analysis was performed with SPSS version 25, using descriptive statistics (frequencies, percentages, means). Comparisons of categorical variables were made using Chi‑square tests, while linear‑by‑linear association was applied to assess dose‑response trends. A p‑value below 0.05 was considered statistically significant.

Results:

Compared to non‑diabetics, diabetic patients had significantly higher CT severity scores (p = 0.004). Poor glycemic control (HbA1c ≥7%) was strongly linked to bilateral lung involvement, larger cavities, disease affecting multiple lobes, and noticeable lymph node enlargement. In particular, those with poor control had a greater number of cavities (p = 0.009); among patients with 3‑4 cavities, 80% were poorly controlled diabetics. There was a positive relationship between HbA1c levels and CT severity scores, with a significant dose‑response trend confirmed by linear‑by‑linear association (p = 0.003). Furthermore, lower lobe involvement was seen more often (51.3%) than upper lobe involvement (40.7%), pointing to an unusual pattern associated with diabetes.

Conclusion:

Diabetics with poor glycemic control is significantly associated with increased radiological severity of pulmonary TB.