To detect early abnormalities in bone mineralization, the lumbar spine bone mineral density (BMD) of diabetic children with a diabetes onset of less than 5 years and treated with a similar insulin treatment scheme was measured at the level of the lumbar spine by dual-energy X-ray absorptiometry (DEXA), a most sensitive technique for detecting osteopenia in children. Fifteen male and 8 female children and adolescents (mean age +/- SD: 12.5+/-3.7 years), 1-5 years after the clinical onset of their diabetes, were studied. Measurements of the lumbar spine (L1-L4) BMD, expressed in gHA/cm2 and as a z-score for age, were performed with a commercial DEXA apparatus (Hologic QDR 1000 W, Hologic Inc., Waltham, USA). Calcium-phosphorus metabolism was studied by measuring the circulating levels of calcium, phosphorus, alkaline phosphatase, osteocalcin, 25-OH-vitamin D and parathyroid hormone and the urinary excretion of calcium and phosphorus. The mean BMD of the studied group was 0.75 (0.16) gHA/cm2 giving a mean z-score of -0.31+/-0.95. Only 1 of the patients had a BMD lower than -2 SD. No sex difference in BMD z-score existed. BMD SD was positively correlated with height SD (R = 0.56, p < 0.005), but not with the age of the patients, the duration of the disease, the degree of metabolic control or the studied parameters of the calcium-phosphorus metabolism. In conclusion, diabetic children have a normal lumbar spine BMD during the first years of the disease, when a good metabolic control and no abnormalities in the calcium-phosphorus metabolism are present. As in normal children, areal BMD by DEXA is highly dependent on the body height, necessitating corrections if abnormalities in skeletal growth or pubertal development exist.