Associated Risk Factors for Latent Tuberculosis Infection in Subjects with Diabetes

Type 2 diabetes mellitus (DM2) confers a higher risk for active tuberculosis (TB). However, information on associated risk factors for latent tuberculosis infection (LTBI) inpatients with DM2 is limited. We conducted a cross-sectional study to elucidate the prevalence of LTBI and its associated factors on Mexican adults with DM2 receiving medical care at the Mexican Social Security Institute (IMSS).

Six hundred patients with DM2 without a prior history of TB from outpatient diabetes clinics were enrolled in the study. The tuberculin-skin-test (TST) was performed. The presence of LTBI was defined by a TST value of ≥ 5 mm. A standardized interview and physical examination were conducted to obtain clinical, demographic, and LTBI risk factor information; all subjects were laboratory tested to determine the presence of exclusion criteria. Microscopic examination of sputum samples and chest x-rays was performed to identify potential active TB. Subjects with any finding suggesting active TB or malignancy were excluded. A logistic regression model was used to identify variables associated with LTBI.

LTBI prevalence among patients with DM2 was 51.3%. Risk factors for LTBI were living with a relative with TB, having been in prison, having hemoglobin values >14 g/dL, and glycosylated hemoglobin (HbA1c) values of > 7%. Blood pressure, economic income, or anthropometric measurements were not associated risk factors.

Over one half of patients with DM harbor LTBI. Exposure to certain environmental conditions and poorly controlled DM2 (HbA1c > 7.0%) were risk factors for having LTBI in persons with DM2.