The prevalence and determinants of active tuberculosis among diabetes patients in Cape Town, South Africa, a high HIV/TB burden setting

Aims Studies addressing the association between diabetes mellitus (DM) and tuberculosis (TB) in sub-Saharan Africa are limited. We assessed the prevalence of active TB among DM patients at a primary care clinic, and identified risk factors for prevalent TB. Methods A cross-sectional study was conducted in adult DM patients attending a clinic in Khayelitsha, Cape Town. Participants were screened for active TB (symptom screening and microbiological diagnosis) and HIV. Results Among 440 DM patients screened, the active TB prevalence was 3.0% (95% CI 1.72-5.03). Of the 13 prevalent TB cases, 53.9% (n = 7; 95% CI 27.20-78.50) had no TB symptoms, and 61.5% (n = 8; 95% CI 33.30-83.70) were HIV-1 co-infected. There were no significant differences in either fasting plasma glucose or HbA 1c levels between TB and non-TB participants. On multivariate analysis, HIV-1 infection (OR 11.3, 95% CI 3.26-39.42) and hemoptysis (OR 31.4, 95% CI 3.62-273.35) were strongly associated with prevalent active TB, with no differences in this association by age or gender. Conclusions The prevalence of active TB among DM patients was 4-fold higher than the national prevalence; suggesting the need for active TB screening, particularly if hemoptysis is reported. Our results highlight the importance of HIV screening in this older population group. The high prevalence of sub-clinical TB among those diagnosed with TB highlights the need for further research to determine how best to screen for active TB in high-risk TB/HIV population groups and settings.