Recent studies have found that the perinatal mortality (PNM) rate in pregnancies complicated by pregestational diabetes remains significantly higher than in the general population. These observations are probably related to lack of optimal glycemic control, and a significant proportion of unplanned pregnancies. The prevalence of pregnancies complicated by type 2 diabetes is increasing. Although these pregnancies are often perceived as a less serious condition, type 2 diabetes appears to be associated with PNM rates that are at least as high as in type 1 diabetic pregnancies. This article reviews the epidemiology, etiology, and recommendations for prevention of PNM in pregnancies complicated by pregestational diabetes.