D-Sorbose is naturally occurring rare sugar. In this study, we examined the effects of dietary D-sorbose in rats. Four-week-old male Sprague-Dawley rats were fed either an AIN-93G-based control diet or a 3% D-sorbose diet for 28 d. Body weight and body fat accumulation were not different between the two diet groups. Dietary supplementation of D-sorbose lowered the serum insulin level (*p<0.05) significantly compared to the control, although the glucose was not changed. In addition, the relative weight of the cecum increased significantly in the D-sorbose group (**p<0.01). These findings suggest that intake of D-sorbose may improve the glucose metabolism by reducing insulin secretion, and D-sorbose can be used as a food ingredient.