The prevalence of diabetes in pregnant women is increasing, with 4% of deliveries in the United States occurring in women with pregestational or gestational diabetes. The proteinuria of late pregnancy is exaggerated in women with diabetes. However, diabetic women with preserved renal function before pregnancy appear to have little risk of deterioration of kidney function during pregnancy. Women with impaired renal function before pregnancy may be at risk for permanent decline of renal function during pregnancy, although it is unclear whether this represents the effect of pregnancy or the natural history of their diabetic renal disease. Preeclampsia, which is more common in women with diabetes, may be difficult to diagnose in this group of women. From the currently available literature, there appears to be no negative effect of pregnancy on the long-term progression of diabetic renal disease if renal function is normal and marked proteinuria is absent, but in light of recent findings in which preeclampsia appears to be associated with an increased risk of end-stage renal disease, large cohort studies will be necessary before this question can be definitively answered.