Tuberculosis and diabetes mellitus comorbidity in Uganda

In Uganda, all study participants underwent initial screening with random blood glucose (RBG) testing, regardless of diabetes mellitus (DM) status. Of the 232 participants, 135 (58.2%) had normoglycemia, 65 (28%) prediabetes, and 32 (13.8%) DM. This is the first Ugandan study to assess DM burden in newly diagnosed TB patients using five screening tests, including the oral glucose tolerance test (OGTT), the diagnostic gold standard. Our study reports the highest DM prevalence among TB patients in Uganda, likely due to the comprehensive screening approach.[1]

Compared to those with tuberculosis (TB) alone, participants with TB-DM comorbidity were older (median age [IQR]: 42.5 [37.0–53.5] vs. 33.5 [25.0–42.0] years; p < 0.001), more likely to live in semi-urban areas (28.1% vs. 12.9%; p = 0.04), and to be former smokers (34.4% vs. 16.9%; p = 0.04). HIV co-infection was less prevalent in the TB-DM group (18.8% vs. 41.8%; p = 0.001). Age ≥40 years was independently associated with TB-DM comorbidity (adjusted odds ratio [AOR] 3.12; 95% CI: 1.35–7.23; p = 0.008), while HIV co-infection was inversely associated (AOR 0.27; 95% CI: 0.10–0.74; p = 0.01).[1]

The apparent protective effect of HIV against DM, observed here and in studies from Tanzania, remains unclear and warrants further research. Conversely, other studies report an increased DM risk in TB-HIV co-infection, potentially due to advanced HIV disease (low CD4 counts), heightened inflammation, insulin resistance, and co-infections such as hepatitis C. Additionally, prolonged survival from antiretroviral therapy (ART) and its metabolic side effects, including dysglycemia, may contribute to increased DM risk.[1]

This study only measured glycemia at baseline, without follow-up, so some hyperglycemia cases may have been transient, potentially leading to an overestimation of DM prevalence. We also did not assess for anemia, which could have affected HbA1c test accuracy.[1]

This systematic review included six studies involving 721 participants from Ethiopia, Kenya, Nigeria, and Egypt, assessing the prevalence of tuberculosis infection (TBI) among individuals with diabetes mellitus (DM). Most studies were small, conducted in tertiary healthcare settings, and lacked comprehensive data on participants' sociodemographic and metabolic profiles. Significant heterogeneity was present across studies, with TBI primarily diagnosed using interferon-gamma release assays (IGRA). The pooled prevalence of TBI was 48% by IGRA and 17% by tuberculin skin test (TST), with an overall pooled prevalence of 40%.[2]

A high burden of TBI was observed in adults with DM across four African regions, particularly among participants aged ≥40 years and those with poor glycemic control (HbA1c > 7%). However, methodological limitations—such as small sample sizes, limited participant data, and potential bias from tertiary facility-based recruitment—warrant cautious interpretation of these findings. Further studies are needed to clarify the relationship between DM and TBI risk in diverse African populations.[2]

References:

1. Kibirige, D., Andia-Biraro, I., Olum, R., Adakun, S., Zawedde-Muyanja, S., Sekaggya-Wiltshire, C. and Kimuli, I., 2024. Tuberculosis and diabetes mellitus comorbidity in an adult Ugandan population. BMC Infectious Diseases, 24(1), p.242.

2. Kibirige, D., Andia-Biraro, I., Kyazze, A.P., Olum, R., Bongomin, F., Nakavuma, R.M., Ssekamatte, P., Emoru, R., Nalubega, G., Chamba, N. and Kilonzo, K., 2023. Burden and associated phenotypic characteristics of tuberculosis infection in adult Africans with diabetes: a systematic review. Scientific Reports, 13(1), p.19894.