Age-Stratified Effects of Diabetes Mellitus on Central Nervous System Tuberculosis Risk and Combined Effects with...

To investigate the relationship between diabetes mellitus (DM) and the risk of central nervous system tuberculosis (CNS-TB), to analyze the age-dependent characteristics of this association, and to assess the combined effects of DM and neutrophil-to-lymphocyte ratio (NLR).

We retrospectively analyzed clinical data of 862 extrapulmonary tuberculosis patients admitted to Fuzhou Pulmonary Hospital from April 2018 to April 2024, including 685 non-CNS extrapulmonary tuberculosis (non-CNS EPTB) patients and 177 CNS-TB patients. Baseline demographic and laboratory characteristics were compared between groups. Age-stratified analysis (≤40 years, 41-60 years, >60 years) was performed to evaluate the age-dependent nature of the association between diabetes and CNS-TB risk. Multivariate logistic regression analysis was used to identify independent risk factors for CNS-TB, and to assess the combined effects and interaction between diabetes and NLR.

The prevalence of DM was significantly higher in the CNS-TB group than in the non-CNS EPTB group (24.29% vs 12.26%, P<0.001), with significantly elevated NLR (P<0.001). Age-stratified analysis revealed that the association between diabetes and CNS-TB risk exhibited significant age dependence, with no significant correlation in the ≤40 years group (OR=1.52, 95% CI: 0.47-4.94, P=0.506), but significant associations in the 41-60 years group (OR=2.80, 95% CI: 1.40-5.63, P=0.003) and >60 years group (OR=2.22, 95% CI: 1.20-4.13, P=0.010). Multivariate analysis confirmed DM (adjusted OR=2.116, 95% CI: 1.382-3.241, P<0.001) and NLR (adjusted OR=1.051, 95% CI: 1.022-1.080, P<0.001) as independent risk factors for CNS-TB. Combined effects analysis demonstrated that patients with both diabetes and high NLR (>4.194) had the highest risk of CNS-TB (adjusted OR=4.833, 95% CI: 2.737-8.535, P<0.001), with a proportion of 38.4%. However, formal interaction analysis indicated no evidence of a statistically significant additive interaction (RERI=0.198, 95% CI: -2.772-3.169, P=0.896).

DM is an independent risk factor for CNS-TB, significantly increasing risk in individuals aged >40 years. DM and NLR independently contribute to CNS-TB risk, supporting clinical risk assessment and prevention strategies incorporating metabolic and inflammatory biomarkers.