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 HbA1c 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.