The impact of diabetes mellitus on pulmonary TB

To compare the clinical characteristics and laboratory results of pulmonary TB (PTB) patients with and without diabetes mellitus (DM) and the relationship between haemoglobin A1C (HbA1c) concentration and mycobacterial load at county level area in Sichuan Province, China.

A retrospective study was performed from January 2018 to July 2019 inJianyang People's Hospital, Sichuan Province. Clinical characteristics and laboratory results of newly diagnosed TB patients were collected. Univariable and multivariable logistic regression analyses were performed. The Kruskal-Wallis test was used to compare HbA1c level and mycobacterial load.

The final sample included 415 patients with TB, of whom 45 were diagnosed with DM (10.8%). Uni-variable logistic regression showed that PTB patients with concomitant DM were more likely to present with haemoptysis, positive acid-fast bacilli (AFB) smear, cavity, higher erythrocyte sedimentation rate (ESR), higher serum C-reactive protein (CRP), lower serum albumin (ALB), or higher fasting blood glucose (FBG). Multivariate logistic regression analyses showed that AFB smear positivity (OR 15.81, 95% CI 3.09-80.95) and FBG (OR 1.88, 95% CI 1.53-2.31) were independent risk factors of DMPTB. The mycobacterial load was heaviest when the HbA1c was 7.9 mmol/L (95% CI 7.35-11.1) and declined along with HbA1c rising up. But it has not been significantly associated with HbA1c.

Patients with PTB over 45 years old, with haemoptysis, positive AFB, cavity, higher ESR, higher CRP, lower ALB or higher FBG are more likely to present with concomitant DM. Patients with PTB with these factors need to be targeted for DM screening. The mycobacterial load has not been significantly associated with HbA1c.