LTBI and diabetes

Tuberculosis (TB) poses distinct public health challenges across different economic contexts. In countries with widespread TB, quick diagnosis and effective treatment are crucial for managing and preventing the disease. As TB becomes less common, more cases are likely to stem from the reactivation of latent TB infections (LTBI). In areas with moderate to low TB rates, the disease tends to cluster in specific high-risk groups. An adaptive strategy tailored to local epidemiological patterns is necessary, with growing attention on the social determinants and risk factors influencing TB.[1]

A study utilizing data from the nationally representative NHANES 2011–2012 survey examined the relationship between diabetes and latent tuberculosis infection (LTBI) in non-institutionalized US adults. The study found that the prevalence of diabetes was 11.4%, prediabetes 22.1%, and LTBI 5.9%. Notably, LTBI prevalence was higher among adults with diabetes (11.6%) compared to those without diabetes (4.6%). Individuals with prediabetes also exhibited a higher LTBI prevalence (7.0%), although this difference was not statistically significant.[3]

The crude odds ratio (OR) for LTBI among adults with diabetes was 2.70, while for those with prediabetes, it was 1.54. After adjusting for potential confounders, diabetes remained significantly associated with LTBI, with an adjusted OR of 1.90. In contrast, prediabetes was not significantly associated with LTBI after adjustment (adjusted OR 1.15).[3]

Further analysis revealed particularly high LTBI prevalence among Hispanics and non-Hispanic Asians with diabetes, and among foreign-born individuals with diabetes, where prevalence reached 30.2%. LTBI was also more common in adults with diabetes who were not using insulin and in those with increasing HbA1c levels, though the association plateaued beyond an HbA1c of 8.5%. While no significant multiplicative interactions were detected, trends suggested a stronger association between diabetes and LTBI among individuals with obesity and those with elevated HDL cholesterol levels.[3]

Diabetes mellitus (DM) significantly heightens the risk of active TB, leads to poorer treatment outcomes, and increases the chance of TB recurrence. Studies show that DM increases TB risk by about twice (RR of 2.03) in low- and moderate-incidence settings. In these countries, DM is more common among the elderly, paralleling the aging population trend. The demographic shift in TB is also towards the elderly, except among migrants. Those with DM, particularly in healthcare settings, are more exposed to TB. Generally, men have a higher proportion of TB linked to DM than women, except in Asian populations. DM impacts TB both by directly increasing individual risk and indirectly by enhancing transmission. Interestingly, obesity appears to reduce TB risk by about two-thirds compared to normal weight, even after accounting for DM and other factors.[1] 

A study was carried out from 2016 to 2019 in a large hospital in metro Atlanta, Georgia, looking at newly diagnosed, HIV-negative adults with type 2 diabetes (T2DM) who had never had tuberculosis (TB). The study compared cases (adults over 21 with T2DM diagnosed within three years) with controls (adults without T2DM). Most participants were African American, with 92.9% of cases and 79.4% of controls. Cases were older, averaging 54 years old compared to 51 for controls. Health-wise, fewer cases smoked daily (24.7% vs. 35.3% in controls), but cases had higher occurrences of high cholesterol, high blood pressure, and obesity.[2]

The study found that latent tuberculosis infection (LTBI) was less common in those with T2DM (9.2%) than in controls (14.7%). After considering age and gender, the likelihood of LTBI in cases was about half that in controls. When looking at blood sugar control, measured by HbA1c, there wasn't a big difference between those with or without LTBI in either group. However, higher HbA1c levels in people with LTBI were linked to higher QFT nil values, but not with other TB test results. This research sheds light on how T2DM might relate to LTBI among this specific group.[2]

References:

1. Lee, P.H., Fu, H., Lee, M.R., Magee, M. and Lin, H.H., 2018. Tuberculosis and diabetes in low and moderate tuberculosis incidence countries. The International Journal of Tuberculosis and Lung Disease, 22(1), pp.7-16.

2. Salindri, A.D., Haw, J.S., Amere, G.A., Alese, J.T., Umpierrez, G.E. and Magee, M.J., 2021. Latent tuberculosis infection among patients with and without type-2 diabetes mellitus: results from a hospital case-control study in Atlanta. BMC Research Notes, 14(1), p.252.

3. Barron, M.M., Shaw, K.M., Bullard, K.M., Ali, M.K. and Magee, M.J., 2018. Diabetes is associated with increased prevalence of latent tuberculosis infection: Findings from the National Health and Nutrition Examination Survey, 2011–2012. Diabetes research and clinical practice, 139, pp.366-379.