Abstract
BACKGROUND: A growing body of evidence supports the role of type 2 diabetes as an individual-level risk factor for tuberculosis (TB), though evidence from developing countries with the highest TB burdens is lacking. In developing countries, TB is most common among the poor, in whom diabetes may be less common. We assessed the relationship between individual-level risk, social determinants and population health in these settings. METHODS: We performed individual-level analyses using the World Health Survey (n = 124,607; 46 countries). We estimated the relationship between TB and diabetes, adjusting for gender, age, body mass index, education, housing quality, crowding and health insurance. We also performed a longitudinal country-level analysis using data on per-capita gross domestic product and TB prevalence and incidence and diabetes prevalence for 1990-95 and 2003-04 (163 countries) to estimate the relationship between increasing diabetes prevalence and TB, identifying countries at risk for disease interactions. RESULTS: In lower income countries, individuals with diabetes are more likely than non-diabetics to have TB [univariable odds ratio (OR): 2.39; 95% confidence interval (CI): 1.84-3.10; multivariable OR: 1.81; 95% CI: 1.37-2.39]. Increases in TB prevalence and incidence over time were more likely to occur when diabetes prevalence also increased (OR: 4.7; 95% CI: 1.0-22.5; OR: 8.6; 95% CI: 1.9-40.4). Large populations, prevalent TB and projected increases in diabetes make countries like India, Peru and the Russia Federation areas of particular concern. CONCLUSIONS: Given the association between diabetes and TB and projected increases in diabetes worldwide, multi-disease health policies should be considered.