Epidemiology of latent tuberculosis infection among patients with and without diabetes mellitus

Abstract

Background. Individuals with type 2 diabetes mellitus (DM) are at a greater risk of tuberculosis (TB) reactivation. There is a paucity of information about the risk factors associated with latent tuberculosis infection (LTBI) in patients with diabetes. Objective. We conducted an observational study to compare the prevalence and risk factors associated with LTBI factors in Malaysian adults with and without DM. Methods. Four hundred and four patients with DM and 359 patients with non-DM at a regional primary care clinic were recruited as participants in this case-control study. The tuberculin sensitivity test (TST) was performed. The presence of LTBI was defined by a TST value of 10 mm in DM patients and 10 mm in the non-DM group. A logistic regression model was used to identify variables associated with LTBI. Results. There was no statistical significant difference in the prevalence rates seen between the DM and non-DM group of the study. LTBI prevalence among patients with DM was 28.5%. The proportion of patients in the non-DM group with LTBI was 29.2%. When a critical cut-off of 8 mm was used, the adjusted odds ratio of LTBI in DM patients was 1.88 (95% confidence interval: 1.22- 2.82). Smoking was an independent risk factor for LTBI regardless of DM status. HbA1c levels or anthropometric measurements were not associated with LTBI in diabetic patients. Conclusions. There is no significant risk of contracting LTBI in DM patients using the standard 10- mm TST cut-off. Nonetheless, using lower cut-offs in a DM population appear valid. Smoking is an important predictor of LTBI.