Maternal diabetes constitutes an unfavorable environment for the development of the fetus. The concept that exposure in utero to a hyperglycemic environment has both a short- and a long-term impact in the offspring is notably demonstrated by animal studies. Animal models for diabetes and pregnancy offer various ranges of hyperglycemia, which can lead to fetal organ alterations, congenital malformations, and micro- or macrosomic fetuses and affect the offspring later in life. The purpose of this review is to give a comprehensive view of the most frequently studied animal models of diabetes and to demonstrate how animal models have permitted to elucidate some mechanisms involved in the pathogenesis of diabetes.