Diabetes Mellitus and Tuberculosis Treatment Outcomes: Interaction Assessment Between Hyperglycemia and Human Immunodeficiency Virus in the State of Georgia, 2015-2020.

Background: Diabetes mellitus and human immunodeficiency virus (HIV) are independent risk factors for poor outcomes among people with tuberculosis (TB). To date, information on the joint impact of diabetes and HIV on TB outcomes is limited. We aimed to estimate (1) the association between hyperglycemia and mortality and (2) the effect of joint exposure to diabetes and HIV on mortality. Methods: We conducted a retrospective cohort study among people with TB in the state of Georgia between 2015 and 2020. Eligible participants were 16 or older, did not have a previous TB diagnosis, and were microbiologically confirmed or clinical cases. Participants were followed during TB treatment. Robust Poisson regression was used to estimate risk ratios for all-cause mortality. Interaction between diabetes and HIV was assessed on the additive scale using the attributable proportion and on the multiplicative scale with product terms in regression models. Results: Of 1109 participants, 318 (28.7%) had diabetes, 92 (8.3%) were HIV positive, and 15 (1.4%) had diabetes and HIV. Overall, 9.8% died during TB treatment. Diabetes was associated with an increased risk of death among people with TB (adjusted risk ratio [aRR] = 2.59; 95% confidence interval [CI], 1.62-4.13). We estimated that 26% (95% CI, -43.4% to 95.0%) of deaths among participants with diabetes mellitus and HIV were due to biologic interaction. Conclusions: Diabetes alone and co-occurring diabetes and HIV were associated with an increased risk of all-cause mortality during TB treatment. These data suggest a potential synergistic effect between diabetes and HIV.