Enhanced DM management reduce the risk and improve the outcome of TB

Lo, H.Y., Yang, S.L., Lin, H.H., Bai, K.J., Lee, J.J., Lee, T.I. and Chiang, C.Y., 2016. Does enhanced diabetes management reduce the risk and improve the outcome of tuberculosis?. The International Journal of Tuberculosis and Lung Disease, 20(3), pp.376-382.

Diabetic TB patients face higher risks of treatment failure, death, and recurrent TB compared to non-diabetic TB patients.

Patients with diabetes mellitus (DM) enrolled in an enhanced case management program for DM had a lower likelihood of developing TB.

If they developed TB, patients in the enhanced DM management program experienced better outcomes than those not enrolled in the program.

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In low and moderate TB incidence countries, TB often concentrates in specific groups, notably those with diabetes. In Taiwan, diabetes mellitus (DM) is the leading risk factor for pulmonary TB. After adjusting for confounders, type 2 DM is an independent risk factor for TB nationwide, though the association is stronger for type 1 DM. Poor glycemic control can increase the hazard ratio for TB in adults under 65, with men and individuals aged 55–64 at greater risk. TB patients with heart failure, ischemic heart disease, stroke, hypertension, dyslipidemia, chronic kidney disease, and liver disease are more likely to have DM.

Interestingly, obesity does not increase TB risk despite its link to diabetes. TB incidence and mortality have decreased in Taiwan, yet DM remains the fifth leading cause of death. In newly diagnosed TB patients, those with DM experience higher mortality rates. Proper TB treatment has been shown to improve glycemic control, possibly due to TB-induced hyperglycemia through stress dysglycemia mechanisms. Both anti-TB and antidiabetic treatments may help mitigate hyperglycemia.

Chronic hyperglycemia impairs immunity to M. tuberculosis and affects lung perfusion, reducing immune response in diabetic patients. Those with poor glycemic control (fasting plasma glucose >130 mg/dL) have a higher TB hazard, while those with good control (FPG <130 mg/dL) do not significantly differ from non-diabetics. Diabetics with HbA1c >7% are more likely to be smear-positive for TB compared to those with HbA1c <7%.

Initial two-year metformin (MET) use reduces active TB risk, with a greater effect at higher dosages. MET also reduces DM-related mortality during TB treatment. Ezetimibe, a cholesterol-lowering drug, shows promise as adjunctive therapy for TB by lowering latent TB prevalence, intracellular lipid content, and M. tuberculosis growth in leukocytes among diabetic patients. While DM significantly raises the odds of multidrug-resistant TB (MDR-TB), the impact of glycemic control on MDR-TB outcomes remains unclear.

Source: Wang, M.C. and Cervantes, J., 2019. Glycemic control in tuberculosis: lessons learned from Taiwan. Asian Pacific Journal of Tropical Medicine, 12(10), pp.438-441. https://journals.lww.com/aptm/fulltext/2019/12100/glycemic_control_in_tuberculosis__lessons_learned.2.aspx