Increased risk of latent tuberculous infection among persons with pre-diabetes and diabetes mellitus

SETTING: Although diabetes mellitus (DM) is an established risk factor for active tuberculosis (TB) disease, little is known about the association between pre-DM, DM, and latent tuberculous infection (LTBI). OBJECTIVE: To estimate the association between DM and LTBI. DESIGN: We conducted a cross-sectional study among recently arrived refugees seen at a health clinic in Atlanta, GA, USA, between 2013 and 2014. Patients were screened for DM using glycosylated-hemoglobin (HbA1c), and for LTBI using the QuantiFERON-TB (QFT) test. HbA1c and QFT results, demographic information, and medical history were abstracted from patient charts. RESULTS: Among 702 included patients, 681 (97.0%) had HbA1c and QFT results. Overall, 54 (7.8%) patients had DM and 235 (33.8%) had pre-DM. LTBI was prevalent in 31.3% of the refugees. LTBI prevalence was significantly higher (P < 0.01) among patients with DM (43.4%) and pre-DM (39.1%) than in those without DM (25.9%). Refugees with DM (adjusted OR [aOR] 2.3, 95%CI 1.2-4.5) and pre-DM (aOR 1.7, 95%CI 1.1-2.4) were more likely to have LTBI than those without DM. CONCLUSION: Refugees with DM or pre-DM from high TB burden countries were more likely to have LTBI than those without DM. Dysglycemia may impair the immune defenses involved in preventing Mycobacterium tuberculosis infection.