Some of the proposed causes of the high incidence of indeterminate results include delayed M. tuberculosis-specific IFN-γ production in the lymph nodes of diabetic mice, as measured by enzyme-linked immunospot (ELISPOT), and decreased levels of M. tuberculosis-specific antigen-stimulated IFN-γ production in the whole blood of DM patients with latent TB infection [31, 32]. Here, IFNG is linked to diabetes mellitus.