Is Pregnancy Outcome Worse in Type 2 Than in Type 1 Diabetic Women?

Most research on pregestational diabetes has focused on type 1 diabetes, and surprisingly little knowledge exists concerning outcomes of pregnancies of women with type 2 diabetes. A dearth of published data suggest outcomes similar to those of type 1 diabetic women (1,2), although recent studies report poorer outcomes in women with type 2 diabetes (3–7).

We retrospectively compared maternal and perinatal outcomes of 93 consecutive singleton pregnancies in women with type 2 diabetes and 532 consecutive singleton pregnancies in women with type 1 diabetes referred to the Diabetes and Pregnancy Unit at University Hospital La Paz from 1984 to 2004.

Women with type 2 diabetes were significantly older ([means ± SD] 31.8 ± 5.5 vs. 29.4 ± 4.7 years, P < 0.001), were more frequently obese (45.2 vs. 9%, P < 0.001), and had a shorter duration of diabetes (5.7 ± 6 vs. 11.8 ± 7.1 years, P < 0.001). The rate of preconceptional care (16.1 vs. 22.6%, P = 0.175) and gestational age at first visit (12.1 ± 6.8 vs. 11.5 ± 6.9 weeks’ gestation, P = 0.529) did not differ between type 2 and type 1 diabetic women. Maternal and perinatal outcomes are shown in Table 1. Insulin requirements and HbA_1c (A1C) were lower during all three trimesters of pregnancy in type 2 diabetic women. Maternal weight gain and the rate of caesarean deliveries were lower in type 2 diabetes. Gestational age at birth was significantly higher and the rate of large infants for gestational age lower in infants of women with type 2 diabetes. The rates of perinatal mortality and major congenital malformations were comparable in both groups. First-trimester A1C in type 2 and type 1 diabetic mothers with perinatal mortality was 9.9 and 8.1 ± 1.2%, respectively. Among pregnancies complicated by major congenital malformations, first-trimester A1C was >7% in 84% of women with type 1 diabetes and only in one woman (16.7%) with type 2 diabetes (P = 0.006). Neonatal distress respiratory syndrome was more frequent in infants of mothers with type 1 diabetes.

In our study, pregnancy outcomes in type 2 diabetic women were, if anything, similar to those with type 1 diabetes. In fact, women with type 2 diabetes had lower rates of large infants for gestational age, neonatal respiratory distress syndrome, and caesarean delivery.

As in some of the studies available, we found no significant differences in perinatal mortality or major congenital malformations between women with type 2 and type 1 diabetes (1–2). However, the results of five recent publications (3–7) suggest that type 2 diabetes could even represent a higher risk of perinatal mortality or congenital malformations than that conferred by type 1 diabetes. Similar rates of preconceptional care in women with type 1 and type 2 diabetes in our study could explain this discrepancy, as could the fact that gestational age at first visit to the clinic was comparable in both type 1 and type 2 diabetic women who did not undergo preconceptional care.

In our study, congenital malformations in type 2 diabetes were not related to poor first-trimester metabolic control in most cases. The concurrence in women with type 2 diabetes of factors other than glycemic control, such as obesity and older age, may account for this finding (8).

In conclusion, our study shows that pregnancy outcomes in type 2 diabetes are better than in type 1 diabetes when type 2 diabetic women receive as much intensified medical treatment during preconception and pregnancy as that given to type 1 diabetic women.