Embryonic malformations in rats, resulting from maternal diabetes: preliminary observations

Diabetes mellitus was induced in female Wistar rats by injections of either alloxan or streptozotocin, and their embryos were found to have significantly higher incidences (7.5%) of brain and heart abnormalities (non-closure of neural folds, and deformities of heart chambers) at mid-gestation than controls (2.2%). There were also increased numbers of resorptions (25% in diabetic animals: 7.2% in controls). Both drugs produced similar abnormalities. External and X-ray examination of 488 foetuses from streptozotocin-treated animals at 20 days showed eight cases of exomphalos, two cases of micrognathia with tongue protrusion, and 34 cases of incomplete sacral ossification. This last deformity occurred also in foetuses of mildly diabetic animals, and has been seen occasionally in infants of human diabetic mothers. Other evidence suggests that skeletal deformities may be due to hyperinsulinism in the foetuses of diabetic mothers. Even a mild or pre-diabetic condition may set the foetus at risk.