What is the link between diabetes and the immune system fighting tuberculosis?

Diabetes mellitus (DM) impairs the body's immune defenses, making it harder to fight infections like tuberculosis (TB). A systematic review of 81 studies found that DM disrupts both innate and adaptive immune responses, alters cytokine signaling, and impairs granuloma function, leading to reduced control of Mycobacterium tuberculosis ⁶. This means people with diabetes are more susceptible to TB, have more severe disease, and respond more slowly to treatment.

What the research says

The systematic review showed that diabetes causes broad dysregulation of the immune system, affecting how the body responds to TB ⁶. Specifically, DM impairs the formation and function of granulomas, which are structures that wall off TB bacteria, and reduces the ability of immune cells to kill the bacteria ⁶. Even pre-diabetes and intermediate hyperglycemia may compromise TB immunity ⁶.

Other studies support that diabetes weakens infection defenses. For example, research on surgical patients found that those with diabetes had higher rates of wound infections and delayed healing, partly due to excessive neutrophil extracellular trap (NET) formation mediated by the PADI4 gene ⁵. Another study identified diabetes as an independent risk factor for surgical site infections after spinal surgery ⁴.

Additionally, diabetes is associated with chronic inflammation and oxidative stress, which can further impair immune function ⁷. This pro-inflammatory environment may worsen TB pathogenesis by disrupting normal immune signaling ⁶⁷.

What to ask your doctor

• How does my diabetes control (blood sugar levels) affect my risk for tuberculosis?
• Should I be screened for latent TB infection because I have diabetes?
• What can I do to improve my immune function and reduce infection risk?
• Are there any specific vaccines (like BCG) recommended for people with diabetes?
• If I have TB, how might my diabetes treatment need to be adjusted?