BONE LOSS AND BONE TURNOVER IN DIABETES

There have been conflicting reports about the effect of diabetes on bo ne density. In 1978, we studied 109 patients, 46 with type I and 63 wi th type II diabetes; similar to 12 years later we restudied 35 of the 66 surviving patients. In the original study, radial bone density did not differ significantly between patients with either type of diabetes but was significantly lower than in nondiabetic control subjects. In eight osteopenic patients, bone formation rate and other histological indexes of osteoblast recruitment and function were markedly depressed compared with those in nondiabetic control subjects. In ,patients rem easured similar to 2.5 years (41 patients) and similar to 12.5 years ( 35 patients) after baseline, bone loss had continued at the expected r ate in patients with type I diabetes, with maintenance of the same def icit, but was slower than expected in patients with type II diabetes, such that the initial deficit had been completely corrected. In six of the eight patients who had undergone bone biopsy, one with type I and five with type II diabetes, the mean bone mineral density z-score of the spine and femoral neck similar to 12 years later was >0 and in one subject was significantly higher than normal at both sites. Based on these data and on previous studies, we propose that in patients with d iabetes, low bone formation retards bone accumulation during growth, m etabolic effects of poor glycemic control lead to increased bone resor ption and bone loss in young adults, and low bone turnover retards age -related bone loss. These effects account for low bone density in youn g patients with type I diabetes and normal or increased bone density i n older patients with type II diabetes.