Diabetes severity is strongly associated with the risk of active tuberculosis (TB) in patients with type 2 diabetes, suggests a study published in the journal Respiratory Research.¹ Those taking insulin or those with chronic kidney disease (CKD) are at higher risk of developing new active TB.

This trial was undertaken to examine the association between the severity of diabetes and risk of incident active TB, both pulmonary and extrapulmonary. A total of 2,745,638 people with type 2 diabetes were included in this study. Data of the participants, from 2009 to 2012, was obtained from the Korean National Health Insurance Service (NHIS). Those who had active TB were not included in the trial. A diabetes severity score, ranging from 0 to 5, was calculated using five parameters of the number of oral hypoglycemic agents (OHAs) (≥ 3), insulin use, duration of diabetes (≥ 5 years) chronic kidney disease (CKD) or cardiovascular disease. Each variable was awarded one point.

A total of 21,231 cases of new active TB, which was the primary study outcome, were detected over the median follow-up of 6 years. Patients who developed TB were older (64 vs 57 years), male (66.5 vs 60%) with higher prevalence of heart disease or CKD. They were also less likely to have obesity (BMI; 23.6 vs 24.9 kg/m2). All variables of the diabetes severity score were individually associated with an increased risk of active TB and the risk increased with increasing diabetes severity score. The risk of incident TB was higher in patients with diabetes duration of ≥ 5 years with adjusted hazard ratio (aHR) of 1.25 and those taking ≥ 3 OHAs (aHR 1.28) and those with heart disease (aHR 1.14). The highest risk was attributed to use of insulin (aHR 1.47) followed by CKD (aHR 1.30).

Compared to participants who lacked any parameter (of the severity score), the HR for TB among those who had one parameter was 1.23, for those with two variables, the HR was 1.39 and 1.65 for patients with three parameters. The risk increased 2-folds among those with four and all five parameters with HRs of 2.05 and 2.65 respectively. Among those who scored 2 on the diabetes severity score, the highest HR for TB was seen in patients taking insulin and multiple OHAs or those on insulin and with CKD. “Among the participants with three parameters (score of 3), the highest HR for TB was in those who used insulin and had CKD and DM duration of ≥ 5 year.”

This study reaffirms diabetes as one of the major risk factors for TB. It utilized a diabetes severity score with five clinical parameters to illustrate this association and determined that severity of diabetes was “strongly associated in a dose-dependent manner with the occurrence of active TB”. These parameters are readily available and hence can be used to assess the risk in resource-constrained countries. Patients with diabetes, especially those with higher scores, should be screened for active TB. Patients taking insulin or with CKD may be considered for targeted screening.

Reference

1. Ji Young Kang, et al. Diabetes severity is strongly associated with the risk of active tuberculosis in people with type 2 diabetes: a nationwide cohort study with a 6-year follow-up. Respir Res. 2023 Apr 11;24(1):110. doi: 10.1186/s12931-023-02414-5.