Mineral Metabolism and Bone Mass at Peripheral and Axial Skeleton in Diabetes Mellitus

Bone mineral content (BMC), mineral homeostasis, and diabetes control were evaluated in 31 Caucasian insulin-dependent diabetic patients (disease duration 18.3 ± 7.7 yr, mean ± SD) with normal kidney function. To evaluate bone mass, we performed radiogrammetry and single- and dual-photon absorptiometry. In women, a significantly lower mean BMC was found in the distal radius, at a mixed trabecular-cortical (P < .01) and a cortical (P < .05) site, as well as in the lumbar spine (P < .02). In diabetic men, mean BMC was significantly reduced at the trabecularcortical (P < .01) and cortical (P < .05) sites of the radius but not in the lumbar spine. When expressed as densities (i.e., BMC/width or lumbar BMC/area), only the BMC/width at the radius cortical area was significantly reduced in women (P < .05). The results of the radiogrammetry showed a larger endosteal diameter in the diabetic women, resulting in a significantly lower cortical thickness (P < .05). Diabetic men did not show abnormalities on radiogrammetry. Diabetic patients had diminished serum calcium and phosphorus concentrations (P < .001), whereas serum parathyroid, 25-hydroxyvitamin D₃, and concentrations of both total and free 1,25-dihydroxyvitamin D₃ were normal. No correlation between parameters of diabetes control (HbA₁, insulin dose, and triglycerides) or calcium-regulating hormones and BMC were found. These data confirm that, despite large overlap of individual values, mean bone mass at the peripheral skeleton is significantly decreased in diabetic patients. Moreover, we report that the BMC of the lumbar spine is significantly reduced in female diabetic patients.