Context: Glycemic disturbance is usually less severe in pregnant women with type 2 than in those with type 1 diabetes mellitus (DM). Nevertheless, a worse perinatal outcome in women with type 2 DM has been reported in some studies.

Objective: Our objective was to review maternal and fetal outcomes in pregnant women with type 2 vs. type 1 DM.

Study Selection: We conducted a systematic review of papers providing original data on pregnancy outcomes in both type 2 and type 1 DM (Medline search of the period January 1, 1987, to June 30, 2008). Two independent investigators considered papers for eligibility, and a third one solved discrepancies.

Data Extraction: Metaanalysis tools were used to compare four main outcomes (major congenital malformations, stillbirth, and neonatal and perinatal mortality) and 15 secondary ones (five maternal, 10 fetal). Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelines were used to assess quality.

Data Synthesis: Thirty-three studies qualified for inclusion of 3743 citations retrieved. Women with type 2 DM had lower glycated hemoglobin (HbA1c) at booking and throughout pregnancy but a higher risk of perinatal mortality [odds ratio (OR) 1.50, 95% confidence interval (CI) 1.15–1.96] without significant differences in the rates of major congenital malformations, stillbirth, and neonatal mortality. As to secondary outcomes, women with type 2 DM had less diabetic ketoacidosis (OR 0.09, 95% CI 0.02–0.34) and cesarean section (OR 0.80, 95% CI 0.59–0.94) without differences in other outcomes.

Conclusions: Despite a milder glycemic disturbance, women with type 2 DM had no better perinatal outcomes than those with type 1, indicating that type 2 DM in pregnancy is a serious condition.