Glucose driven bacterial persistence in extensively drug-resistant tuberculosis with diabetes

Background Diabetes mellitus (DM) disrupts the metabolic environment of extensively drug-resistant tuberculosis (XDR) patients, promoting mycobacterial persistence. Key factors influencing bacterial clearance remain unclear. This study aimed to identify critical host factors and assess the therapeutic value of intensive glucose control. Method A 48-month single-center retrospective cohort study compared sputum smear conversion (bacterial clearance) between 57 XDR-only (XDR) and 84 XDR with DM (XDR + DM) patients (similar treatment, consistent in vitro MIC resistance profiles). Kaplan–Meier analysis, Cox regression, generalized linear models, and mediation analysis were used to explore associations between diabetic status, blood glucose (GLU) levels, and bacterial clearance, as well as the impact of glucose control on treatment progression. Results Compared with XDR patients, the XDR + DM group exhibited a significantly lower bacterial clearance rate (80.7% vs. 45.2%) and longer median clearance time (6 vs. 12 months), despite comparable baseline smear grades. Crucially, XDR + DM patients displayed distinct immunometabolic dysregulation, characterized by elevated inflammatory markers (CRP) and a disrupted CD4+ /CD8+ T-cell balance (increased CD4+, decreased CD8+ counts). Multivariable analysis identified hyperglycemia as the primary driver of delayed clearance (aHR = 1.48, 95% CI: 1.23–1.77, p 0.001), serving as a significant mediator between DM and impaired outcomes (mediation effect: -0.82, p = 0.006). A glucose “dose–response” relationship was observed: severe hyperglycemia (GLU ≥ 11.1 mmol/L) markedly increased clearance delay risk (aHR = 5.29, p 0.001), whereas optimal control (GLU 7 mmol/L) mitigated these disadvantages. Conclusion Dysregulated glucose metabolism and subsequent immune imbalance in diabetes are key drivers of delayed bacterial clearance in XDR patients, independent of the anti-tuberculosis regimen. Precise glucose control should be regarded as a core strategy, on a par with anti-XDR treatment.