Many authors have described abnormalities of calcium homeostasis in type I diabetes mellitus, but data in the literature are conflicting. Consequently we studied calcium, phosphorus and magnesium (in serum and urine), parathyroid hormone, calcitonin and 25-hydroxyvitamin D (25-OHD) levels in 21 prepubertal diabetic patients and in 21 sex- and age-matched controls. We did not find any significant difference of all the aforementioned parameters between diabetics and controls. Also the value of 25-OHD was similar in diabetic and healthy subjects (24.33 +/- 6.04 vs 22.09 +/- 5.01 ng/ml). The results suggest that the principal parameters of calcium metabolism are normal in prepubertal diabetic children.