Embryonic growth impaired by maternal hypoglycemia during early organogenesis in normal and diabetic rats.

The effect of maternal hypoglycemia on early organogenesis was studied in normal and diabetic rats. Female Wistar rats were made diabetic by an intravenous injection of streptozotocin (45 mg/kg) 2-3 weeks before conception. On day 9.5 or 10.5 of embryo development, both control and diabetic dams received saline or Actrapid human insulin (400 mU/rat) intraperitoneally after 19-h starvation. The fasting plasma glucose levels in diabetic dams decreased from approximately 23 to 8 mM. Hypoglycemia as low as 3.5 mM was maintained for 60 min in insulin-treated mother rats. Pregnancy was terminated on day 11.6 of embryo development. A significant growth retardation was found in diabetic embryos as compared with normal embryos. Maternal hypoglycemia lowered the DNA content in normal but not diabetic embryos, while the teratogenic effect of maternal hypoglycemia was not pronounced in either normal or diabetic embryos. These data may suggest that maternal hypoglycemia in vivo in early pregnancy influences the embryogenesis but not teratogenesis of rat embryos.