Diabetes is a frequent complication of pregnancy. Type 1 diabetes is associated with an increased incidence of preeclampsia and pregnancy-induced hypertension. When renal dysfunction is present, the incidence of these complications is remarkably increased. White's class, poor glycemic control during the first half of pregnancy, and early blood pressure elevation are also independent risk factors for developing preeclampsia. Whether gestational diabetes increases the background incidence of preeclampsia is still debated. Because therapeutic interventions such as low-dose aspirin and antioxidants have not been shown to be effective, preventive measures rely on tight blood glucose control, as well as adequate blood pressure treatment.