Patients with diabetes mellitus (DM) show an increased susceptibility to bacterial infections due to the presence of neutrophil dysfunction. Susceptibility to tuberculosis has also been reported in such patients, however, the reason remains unclear. This study measured the production of interleukin-1 beta (IL-1 beta), tumor necrosis factor alpha (TNF alpha) and interleukin-6 (IL-6) by the peripheral monocytes of patients diagnosed with pulmonary tuberculosis accompanied by DM (TB+DM) and patients without DM complications (TB) using age-matched, healthy control subjects for comparison. Also examined was the relationship between cytokine production and DM control. The results were as follows: (1) The production of IL-1 beta, TNF alpha and IL-6 in TB patients was significantly higher than that observed in the healthy control subjects. (2) The production of IL-1 beta, TNF alpha and IL-6 in TB+DM patients was significantly lower than that observed in the TB patients. (3) The production of IL-1 beta and TNF alpha in TB+DM patients with poor control was significantly lower than that observed in the patients with good control. (4) The TNF alpha production had a significant inverse correlation to HbA1c in the TB+DM patients. This study demonstrated that the production of cytokines is impaired in TB+DM patients and suggests a close correlation between tuberculosis immunity and DM.