Poor glycemic control among people with diabetes mellitus is associated with tuberculosis infection: a cross-sectional study in Nepal

Background: Diabetes mellitus (DM) raises the risk of contracting Tuberculosis (TB) infection and progressing to TB disease. Screening people with diabetes for TB infection and offering preventive treatment can, therefore, minimize the likelihood of progression to TB disease. This study aimed to test if glycemic control among patients with diabetes mellitus presenting to a tertiary care teaching hospital in Nepal is associated with tuberculosis infection.

Methods: This cross-sectional study was conducted among patients aged ≥ 18 years, with a self-reported diabetes mellitus or HbA1C value of ≥ 6.5%, at a tertiary facility in Kathmandu, Nepal. Participants underwent Chest X-rays and TB symptoms screening for TB disease. TB infection status was identified in those without TB disease by an induration of ≥ 10 mm in the Tuberculin Skin Test (TST). Clinical, social, anthropometric, and vaccination information were abstracted. Multiple logistic regression models were used.

Results: Pulmonary TB disease was found in 19 of the 473 patients screened (4.0%) of whom 18 were bacteriologically confirmed. Of the 422 patients analysed, the median age was 54.5 (IQR 47-64.7) years, 316 (74.9%) had poor glycemic control and 193 patients had positive TST (TB infection prevalence – 45.7%). Individuals with poor glycemic control had more than three times the odds of testing TST-positive compared to those with good glycemic control (OR 3.30 [95% CI: 1.78-6.44]), after adjusting for relevant covariates.

Conclusions: TB infection and disease prevalence remain high in people with diabetes mellitus even with bidirectional screening policies and widespread metformin use. Individuals with poorly controlled diabetes mellitus could be a priority group for targeted TB infection testing and preventive treatment.

Clinical trial number: Not applicable.