Impaired intestinal active calcium absorption and reduction of serum 1alpha, 25(OH)2D3 in streptozotocin-induced diabetic pregnant rats with hypocalcemia in their fetuses.

PURPOSE: The effects of maternal diabetes mellitus on fetal hypocalcemia were studied in streptozotocin-induced diabetic rats. MATERIALS AND METHODS: Experiments were performed using Wistar rats rendered diabetic with streptozotocin. Treatment with insulin was started in six diabetic pregnant rats after diabetes induction. On day 21 of gestation, cesarean section was performed and serum ionized calcium, parathyroid hormone and 1alpha, 25-dihydroxyvitamin D3 were measured and the active intestinal calcium absorption was measured in mother rats using the everted gut sac technique. RESULTS: In untreated diabetic pregnant rats, serum 1alpha, 25-dihydroxyvitamin D3 and the active intestinal calcium absorption were significantly decreased, and the placental calcium transfer was disturbed compared with the control and insulin-treated groups. Furthermore, serum ionized calcium levels were markedly reduced in fetuses from untreated diabetic pregnant rats. However, these abnormalities of calcium metabolism in untreated diabetic rats could be corrected by treatment with insulin. CONCLUSIONS: These data indicate that diabetes mellitus in pregnant rats a contribute to negative calcium homeostasis which is probably related to the development of fetal hypocalcemia.