The impact of diabetes and pre-diabetes on prevalence of Mycobacterium tuberculosis infection among household contacts of active tuberculosis cases in Ethiopia Open Access

Smith, Alison Grace Carswell (Spring 2022)

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Background: Whether diabetes affects the risk of developing latent tuberculosis (TB) infection following exposure to Mycobacterium tuberculosis is incompletely understood. We assessed the relationship of diabetes or pre-diabetes and latent TB infection among the close and household contacts (HHCs) of patients with active pulmonary TB disease in Addis Ababa, Ethiopia.


Methods: In this cross-sectional study among close and HHCs of persons with active TB, we performed an interferon-γ release assay (IGRA), TB symptom screening, and a point-of-care glycosylated hemoglobin test (HbA1c). Diabetes status was classified into diabetes (HbA1c ≥6.5% or self-reported diagnosis), pre-diabetes (5.7–6.4%), and euglycemia (5.6%). Latent TB infection (LTBI) was defined as a postitive IGRA and lack of TB symptoms. Multivariate logistic regression was used to determine the association of pre-diabetes and diabetes with latent TB infection.


Results: Among 597 study participants, 123 (20.6%) had dysglycemia including 31 (5.2%) with diabetes and 92 (15.4%) with pre-diabetes (n=92); 423 (70.9%) were diagnosed with latent TB infection. Twelve (38.7%) of 31 HHCs with diabetes were previously undiagnosed. The prevalence of latent TB infection among HHCs with diabetes, pre-diabetes and euglycemia was 27/31 [87.1%], 67/92 [72.8%], and 329/474 [69.4%], respectively. Prevalence of latent TB infection was significantly higher among HHCs with diabetes compared to HHCs with euglycemia (prevalence difference 17.7% [95% CI 5.2-30.2%], odds ratio 2.97 [95% CI 1.14-10.2]). In multivariable analysis, HHCs with diabetes had a higher prevalence of latent TB infection (adjusted odds ratio 1.60, 95% CI 0.56-5.79) but the difference compared to those without dysglycemia was not statistically significant.


Conclusion: We found very high rates of latent TB infection among HHCs of active TB cases in Addis Ababa. Furthermore, HHCs with diabetes were more likely to have latent TB infection than those with euglycemia. Further investigation is needed to assess mechanisms by which DM may increase risk for latent TB infection after M. tuberculosis exposure.

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Figure 1. Study flow diagram illustrating selection of participants 24

Figure 2. Directed acyclic graph model of the relationship of diabetes and LTBI 25

Table 1. Prevalence of diabetes and prediabetes among household contacts 26

Table 2. Diabetes management among household contacts with diabetes 27

Table 3. Summary of household contact characteristics stratified by IGRA result 28

Table 4. Multivariable model for odds of LTBI by diabetes status 30

Table 5. Prevalence differences of LTBI among participants with diabetes as compared to euglycemia or pre-diabetes, stratified by sex, age, and BMI 31

Table 6. Multivariable model for odds of LTBI by diabetes status, with age interaction terms 32

Table 7. Quantitative IFN- γ responses in QuantiFERON-TB Gold Plus testing of household contacts with LTBI 33

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