BMI, diabetes, and risk of tuberculosis

The relationship between obesity, diabetes mellitus (DM), and tuberculosis (TB) is multifaceted and often contradictory. Numerous studies highlight that a higher body mass index (BMI) is generally associated with a lower risk of pulmonary TB. This potential protective effect may stem from better nutritional reserves and energy stores in individuals with overweight or obesity. However, this benefit appears to plateau or even reverse at extremely high BMI levels, particularly in specific populations such as young women. These findings suggest that there may be an optimal BMI range where the protective effects are most pronounced. Additionally, demographic factors like age and gender further influence this association, with older adults and women showing stronger protective effects from higher BMI.

Diabetes mellitus, in contrast, consistently emerges as a strong and independent risk factor for TB, regardless of BMI. Individuals with DM are significantly more likely to develop TB, indicating that metabolic dysfunction plays a critical role in TB susceptibility. Some studies suggest that DM may act as a mediator between BMI and TB risk, with obesity-related metabolic impairments such as impaired fasting glucose (IFG) potentially exacerbating the progression of TB. Interestingly, individuals who are both obese and diabetic may not experience a heightened TB risk compared to non-diabetic individuals with normal BMI, indicating a complex interplay of protective and risk factors. Moreover, the association between BMI and TB is stronger for active TB cases than for latent infections (LTBI), highlighting differences in disease dynamics.

These insights have important implications for both clinical practice and public health policy. Clinicians must consider not just BMI, but also the presence of metabolic conditions like DM when assessing a patient's risk for TB. Public health strategies should aim to address the shared and synergistic effects of obesity and DM in TB prevention efforts, particularly among vulnerable populations. While obesity may offer some protection against TB, it also poses other health risks and can contribute to metabolic disorders that increase TB risk. Therefore, a balanced, individualized approach to managing body weight and metabolic health is essential. Further research is needed to clarify the underlying biological mechanisms and to develop targeted interventions that can effectively reduce TB incidence while also addressing the growing global burden of obesity and diabetes.

Source: Herman, D., Machmud, R. and Lipoeto, N.I., 2025. Unraveling the Link between Obesity and Tuberculosis: A Systematic Review of the Underlying Mechanisms. Bioscientia Medicina: Journal of Biomedicine and Translational Research, 9(2), pp.6453-6466.