Diabetes mellitus is considered as a risk factor for fractures, and there are some reports showing that metabolic effects of poor glycemic control resulted in lower bone turnover. Previous studies have revealed that this reduction of bone turnover increases bone fragility, independently of bone mineral density, so that the mechanisms of diabetic osteopahty seem to be more closely related to bone quality than bone quantity. The mechanisms of the preventive effect on fractures by vitamin K treatment should be related to amelioration of bone quality via increasing amounts of carboxylated osteocalcin. Therefore, administration of vitamin K(2) (menatetrenone) to the patients with diabetic osteopathy will be beneficial in order to improve the impaired bone quality and to reduce fracture risk.