Association between Mycobacterium tuberculosis sensitization and insulin resistance among US adults screened for type 2 diabetes mellitus.

BACKGROUND: Type 2 diabetes mellitus (T2DM) may be a long-term sequela of infection with Mycobacterium tuberculosis (Mtb) by mechanisms that remain to be fully explained. We evaluated the association between Mtb sensitization and T2DM and, via mediation analysis, the extent to which it is mediated by insulin resistance and/or β-cell failure. METHODS: Adults were assessed for T2DM by fasting plasma glucose, 2-hour oral glucose tolerance testing, and hemoglobin A1c; β-cell dysfunction and insulin resistance by homoeostasis model assessment 2; and Mtb sensitization by tuberculin skin testing. Associations between Mtb sensitization and T2DM were modeled with probit regression and decomposed into indirect effects of β-cell dysfunction and insulin resistance. Analyses were adjusted for sociodemographic, behavioral, and clinical characteristics. RESULTS: We included 1843 adults. Individuals with Mtb sensitization were older than those without Mtb (median [IQR], 54 [39-64] vs 47 [33-62] years). As compared with being uninfected, Mtb sensitization was associated with T2DM (adjusted absolute risk difference, 9.34% [95% CI, 2.38%-15.0%]; P < .001) and increased insulin resistance (adjusted median difference, 0.16 [95% CI, .03-.29]; P = .014) but not β-cell dysfunction (adjusted median difference, -3.1 [95% CI, -10.4 to 4.3]; P = .42). In mediation analyses, insulin resistance mediated 18.3% (95% CI, 3.29%-36.0%; P = .020) of the total effect of the association between Mtb sensitization and T2DM. CONCLUSIONS: Definitive prospective studies examining incident T2DM following tuberculosis are warranted. Notwithstanding, our findings suggest that exposure to Mtb may be a novel risk factor for T2DM, likely driven by an increase in insulin resistance.