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

BACKGROUND: Many have the rising coincidence of diabetes mellitus (DM) and endemic tuberculosis (TB). We evaluated whether the severity of diabetes is associated with an increased risk of active TB infection. METHODS: Using a nationally representative database from the Korean National Health Insurance System, 2, 489, 718 people with type 2 DM who underwent a regular health checkup during 2009–2012 were followed up until the end of 2018. The diabetes severity score parameters included the number of oral hypoglycemic agents (≥ 3), insulin use, diabetes duration (≥ 5 years), and the presence of chronic kidney disease (CKD) or cardiovascular disease. Each of these characteristics was scored as one point, and their sum (0–5) was used as the diabetes severity score. RESULTS: We identified 21, 231 cases of active TB during a median follow-up of 6.8 years. Each parameter of the diabetes severity score was associated with an increased risk of active TB (all P < 0.001). Insulin use was the most significant factor related to the risk of TB, followed by CKD. The risk of TB increased progressively with increasing diabetes severity score. After adjusting for possible confounding factors, the hazard ratio (95% confidence interval) for TB were 1.23 (1.19–1.27) in participants with one parameter, 1.39 (1.33–1.44) in those with two parameters, 1.65 (1.56–1.73) in those with three parameters, 2.05 (1.88–2.23) in those with four parameters, and 2.62 (2.10–3.27) in those with five parameters compared with participants with no parameters. CONCLUSION: Diabetes severity was strongly associated in a dose-dependent manner with the occurrence of active TB. People with a higher diabetes severity score may be a targeted group for active TB screening. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12931-023-02414-5.