Glycemic Control and the Risk of Tuberculosis: A Population-based Cohort Study

Abstract

Background: Although diabetes, low body mass index (BMI) and high blood lipid are established risk factors for active tuberculosis, the joint effect of diabetes, BMI and blood lipid is unclear. Methods: We conducted a population-based census in eastern China including 40,311 individuals. We investigated risk factors for incident tuberculosis by excluding tuberculosis at baseline and linking all participants to the Infectious Disease Reporting Management System and Tuberculosis Management Information System of Nanjing City. Follow-up for incident tuberculosis occurred ten years. We matched participants using unique health identity card numbers, name, age, birthdate, and address. We constructed Cox Proportional hazard models adjusting for age, sex, smoking, alcohol use.Results: After ten years follow-up, 143 individuals progressed to tuberculosis. In participants with BMI>24 kg/m2, diagnosed diabetics with fasting blood-glucose (FBG)≥7.0mmol/L showed nearly three-fold increased risk of active TB (HR=3.78, 95%CI: 1.32-10.79, P=0.007), and FBG ≥7.0mmol/L was associated with more than three-fold higher risk of active TB(HR=3.16, 95%CI:1.37-7.28, P=0.007). Among high blood lipid levels, undiagnosed diabetics was related to increase the high risk of TB (HR=3.04, 95%CI: 1.03-8.95, P=0.044) and FBG ≥7.0mmol/L increased nearly two-fold higher risk of TB (HR=2.66, 95%CI: 1.13-6.30, P=0.026). In the linear dose-response analysis, the hazard of TB increased with FBG (with a 1-unit (1-mmol/L) increase in FBG, the hazard of TB increased by 15% (95% CI, 3%–29%). Discussion: In this large population-based cohort study in a medium tuberculosis burden region, we found that diabetes increases the hazard of tuberculosis disease and diabetics with poor glycemic control aggravated this relationship especially in individuals with high level of blood lipid.