FN1 and type 1 diabetes mellitus: Our group and others have previously reported skeletal deficits in adolescents with T1DM.(2–12) In our previous work, lower whole body BMC, FN densities, trabecular vBMD values,(8) and BMC acquisition(9) were predicted by poor metabolic control.(8,9) In animal and in vitro cell models, chronic hyperglycemia is linked to altered osteoblast differentiation and maturation.(15,16) Recently, Thrailkill(35) showed preservation of bone formation by insulin administration during osteogenesis in a mouse model.