Effects of human diabetic serum on the in vitro development of early somite rat embryos

High levels of glucose, beta-hydroxybutyrate (B-HOB), and acetoacetate are known to have embryotoxic and teratogenic effects on rat embryos in culture, especially when added concomitantly to the culture medium. We studied the effects of human serum from different types of diabetes mellitus on the in vitro development of 10 1/2-day-old rat embryos cultured for 48 hours. We used serum from type I diabetes with and without ketoacidosis and type II diabetes either untreated or treated with insulin or with daonil. Type I diabetes without ketoacidosis increased the rate of malformations to 27% vs. 11% in controls. Serum from type I diabetes with ketoacidosis further increased the malformation rate to 44%. The rate of malformations induced by serum of type II diabetes was dependent on the treatment. It was relatively low among embryos cultured on serum from untreated (16%) or treated with daonil (19%) and rose to 27% among embryos cultured on serum from type II diabetes treated with insulin. No significant correlation was found between the rate of malformations and the concentrations of glucose, B-HOB, acetoacetate, and HbA1c in all diabetic sera except serum from type I diabetes with ketoacidosis. We may therefore conclude that for most types of diabetes in humans, neither the high blood glucose concentrations nor the high levels of ketone bodies seem to be the main reason for the high rate of malformations. However, we used cultured rat embryos, and the effects on the human embryo may be different. The results of studies on various experimental animal models in diabetes teratogenicity seem to have only partial relevance to the human situation.