We examined the effects of gamma-aminobutyric acid-rich germinated brown rice (germinated brown rice) on principal indexes of life-style related diseases in 67 volunteers aged 71 +/- 8. They were divided into two groups; germinated brown rice group, which had an equal amount of the germinated brown rice to polished rice for 11 to 13 months, and control group, which had polished rice alone for the same period. Differences of indexes before and after the examination between the two groups were compared. Significant increases in body fat ratio, hemoglobin A1c and mean red cell volume and a significant decrease in mean red cell hemoglobin concentration were observed in the germinated brown rice group. However, there was no difference of changes in body mass index, blood pressure, serum lipid, hepatic and renal functions, bone metabolic markers, bone density, depression score, red blood cell counts, hemoglobin, hematocrit, and homeostasis model assessment of insulin resistance between the two groups. These findings suggested that germinated brown rice might not improve glucose metabolism.