Xin Wang,1,* Yu Song,2,* Na Li,3 JingYi Huo,3 BingBing Wang,3 Xue Jiang,3 YuLiang Zhang3 

1Department of General Internal Medicine, Infectious Disease Hospital of Heilongjiang Province, Harbin City, Heilongjiang Province, 150500, People’s Republic of China; 2Heilongjiang Agricultural Engineering Vocational College, Harbin City, Heilongjiang Province, 150025, People’s Republic of China; 3Department of Clinical Laboratory, Infectious Disease Hospital of Heilongjiang Province, Harbin City, Heilongjiang Province, 150500, People’s Republic of China

*These authors contributed equally to this work

Correspondence: YuLiang Zhang, Department of Clinical Laboratory, Infectious Disease Hospital of Heilongjiang Province, No. 1, Jianshe Street, Hulan District, Harbin City, Heilongjiang Province, 150500, People’s Republic of China, Email YLZ_zhangyuliang02@outlook.com

Objective: The aim of this study was to evaluate lymphocyte subsets and clinical outcomes in patients with pulmonary tuberculosis (PTB) combined with type 2 diabetes mellitus (T2DM).
Methods: Between January 2022 and March 2024, 320 patients aged > 60 years were included, 95 of whom had comorbid DM. Lymphocyte subsets (T-lymphocytes, B-lymphocytes, and natural killer cells, NK) were assessed in both groups of patients using fluorescence-associated cell sorting. Clinical characteristics, drug resistance, regression and lymphocyte subsets were compared in PTB patients with DM versus PTB patients alone. The correlation between lymphocyte subsets-related indices and the above characteristics in PTB patients with DM was analyzed.
Results: Compared with PTB patients alone, PTB patients with comorbid DM had a higher positive rate (81.05% vs 62.67%, P = 0.001), prolonged course of antituberculosis treatment (298 [244, 339] days vs 223 [179, 254], P < 0.001) and a lower cured rate (64.21% vs 75.56%, P = 0.039). Compared with PTB patients only, PTB patients with comorbid DM had higher T-lymphocytes and CD4+ T-lymphocytes (P < 0.001, P = 0.006) and lower NK cells (P < 0.001). In PTB patients with comorbid DM, both treatment-prolonged patients and drug-resistant patients showed reduced NK cells. NK cells were slightly elevated in cured patients, although there was no significant difference (P = 0.082).
Conclusion: Lymphocyte homeostasis is altered in PTB patients with comorbid DM, making them more susceptible to severe clinical manifestations and therapeutic outcomes. Notably, NK cells have been identified as key regulatory cells with a significant impact on prolonged treatment course and drug resistance. This study provides new ideas and methods for individualized treatment of PTB combined with DM in the elderly, which can help to optimize the treatment plan and improve the outcome and quality of life of patients.

Keywords: tuberculosis, diabetes mellitus, lymphocyte subsets, clinical regression