BACKGROUND: There are many studies regarding the effects of insulin on bone metabolism and changes in bone mineral density (BMD) in the setting of diabetes. The effect of prediabetes on BMD is not known. METHODS: A total of 802 men participated in the Korea Rural Genomic Cohort Study (in Geumsan County). According to the results of an oral glucose tolerance test, subjects were classified into normal, prediabetic, and diabetic categories. One hundred twenty-four subjects diagnosed with type 2 diabetes were excluded, leaving 678 subjects for the study inclusion. BMD was estimated with a quantitative ultrasonometer. RESULTS: The average BMD T scores of normal and prediabetic subjects were -1.34 +/- 1.42 and -1.33 +/- 1.30, respectively; there was no significant difference in the BMD T scores between these groups. The BMD T score was inversely associated with age and positively correlated with body weight, body mass index, total cholesterol, low density lipoprotein cholesterol, and HbA1c. On multiple linear regression analysis, low density lipoprotein cholesterol was the only statistically significant variable for prediabetes (beta = 0.007, P = 0.005). On the stepwise regression analysis, age (beta = -0.026, P < 0.001), the body mass index (beta = 0.079, P < 0.001), and low density lipoprotein cholesterol (beta = 0.004, P = 0.016) were significant variables for prediabetes. CONCLUSIONS: There was no significant difference in the BMD T score between the normal and prediabetic subjects. Further studies are needed regarding the association of fracture risk and changes in BMD with the development of overt diabetes.