The effects of insulin and glucose on bone modelling in vitro

The direct effects of insulin and glucose on bone modelling was studied in an in vitro system. 16 day old mice fetal radii and ulnae prelabelled with ⁴⁵Ca were cultured for 48 hr in BGJ medium supplemented with either 4 mg/ml of human serum albumin or 10% fetal calf serum. Insulin at concentrations of 10^-8-10^-10 M induced an increase in the periosteal bone formed as well as in calcium, phosphate and hydroxyproline content. Glucose at concentrations of 200-800 mg/dl decreased bone length, calcium, phosphate and hydroxyproline content. There was no change in the ⁴⁵Ca released into the medium, by either insulin or glucose, implying that these substances have no effect on bone resorption. The results of this study imply that insulin and glucose have a direct effect on bone modelling and that they may be important factors in growth disturbances occurring during diabetic pregnancy.