The invention relates to the use of an Fhl2 nucleic acid for the manufacture of a medicament for the treatment of bone diseases such as osteoporosis. The invention further provides a method for diagnosing a bone disease comprising measuring the level of expression of the Fhl2 gene. The invention also provides the use of a non-human mammal characterized by a decreased level of expression of the Fhl2 gene as an osteoporosis model.