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 less than .01) and a cortical (P less than .05) site, as well as in the lumbar spine (P less than .02). In diabetic men, mean BMC was significantly reduced at the trabecularcortical (P less than .01) and cortical (P less than .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 less than .05). The results of the radiogrammetry showed a larger endosteal diameter in the diabetic women, resulting in a significantly lower cortical thickness (P less than .05). Diabetic men did not show abnormalities on radiogrammetry. Diabetic patients had diminished serum calcium and phosphorus concentrations (P less than .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.