Plasma interleukin (IL)-1β and IL-6 are markers that predict the risk of inflammation in diabetes. In the current study, we examined the relationship between fasting glucose and plasma inflammatory cytokines (IL-1β and IL-6) concentrations in healthy and preclinical middle-aged Japanese men (mean ± SD, 58.7 ± 7.8 years old) divided according to body mass index (<25 kg/m², nonoverweight group; ≥25 kg/m², overweight group). We conducted a cross-sectional study of 413 healthy and preclinical men aged 40 to 69 years who participated in health checkups in Japan. We measured their clinical parameters, lifestyle factors, and plasma IL-1β and IL-6 concentrations. Participants were classified according to their fasting blood glucose levels, and we compared their plasma cytokine levels. Plasma IL-1β and IL-6 levels in nonoverweight subjects were positively and strongly associated with fasting blood glucose and hemoglobin A_1c; in contrast, these cytokines were strongly associated with homeostasis model assessment of insulin resistance and fasting glucose in overweight subjects. Significant positive associations between plasma IL-1β and glucose concentrations were observed within the groups classified according to glucose concentrations, after adjustment for age and body mass index. The results of our current study show that plasma IL-1β levels are strongly associated with fasting blood glucose concentrations in healthy and preclinical nonoverweight and overweight Japanese men.