Perinatal mortality in Type 2 diabetes mellitus.
AIMS: In many parts of the world the number of pregnancies in women with Type 2 diabetes mellitus (DM) now exceeds that in women with Type 1 DM, but there are few data published on perinatal mortality in Type 2 DM. This study reports observational data on perinatal mortality in Type 2 DM from a population with a high background rate of this disorder. METHODS: Over a 12-year period (1985-1997) at the Diabetes Clinic at National Women's Hospital, Auckland, there were 434 pregnancies in women with Type 2 DM (256 known and 178 diagnosed with gestational diabetes mellitus (GDM), but confirmed to have Type 2 DM early post-partum), 160 pregnancies in women with Type 1 DM and 932 in women with GDM. Perinatal mortality was classified as either intermediate fetal death (20-28 weeks' gestation), late fetal death (28 weeks' gestation to term) or early neonatal death (up to 1 month post-partum). RESULTS: The perinatal mortality in Type 2DM was 46.1/1,000, significantly higher than the rates for the general population (12.5), Type 1 DM (12.5) and GDM (8.9) (P < 0.0001). Congenital malformations accounted for only 10% of the perinatal mortality. There was a seven-fold increase in the rate of late fetal death and 2.5-fold increase in the rates of intermediate fetal and late neonatal death. Subjects with Type 2 DM were significantly older and more obese than subjects with Type 1 DM, and presented later to the diabetes service. CONCLUSIONS: Perinatal mortality in Type 2 DM is significantly increased, mainly owing to an excess of late fetal death. Maternal factors such as obesity may be important contributors to the high perinatal mortality. Women diagnosed with GDM who have unrecognized Type 2 DM are also at high risk, but perinatal mortality is low in women with milder degrees of glucose intolerance in pregnancy.