Effects of Maternal Diabetes on Early Embryogenesis: The Role of Insulin and Insulin Therapy

Using the system of whole embryo culture the effects of insulin on early mouse embryogenesis were investigated. Three experimental approaches were employed in which (1) serum from diabetic rats receiving insulin therapy was used as culture medium; (2) insulin was added directly to serum collected from diabetic rats for use as culture medium; (3) insulin was added directly to medium (serum) collected from control rats. Mouse embryos were cultured in each of these media for 24 h and then evaluated for growth and malformations. The results demonstrated that insulin therapy was effective in reducing the incidence of malformations and growth retardation produced by serum from diabetic rats receiving no hormone supplement. However, addition of insulin directly to serum collected from diabetic rats was not effective in reducing the rate of abnormalities produced by this medium. Finally, addition of insulin at extremely high concentrations (10,000 μ/ml) produced no abnormal embryos. Thus, it appears that insulin therapy is successful in reducing malformation rates and that the hormone itself is not teratogenic in this system.