Importance of diagnosis time on pregnancy outcomes in pregnant women with pre-gestational diabetes mellitus

Objective: To analyze the characteristics of pregnant women with pre-gestational diabetes mellitus (PGDM) who had missed diagnosis prior to pregnancy, and to evaluate the effects of diagnosis time on pregnancy outcomes in pregnant women with PGDM. Materials and Methods: A total of 822 pregnant women who were diagnosed with PGDM were conducted in this study. They were divided into two groups, including pre-pregnancy diagnosis group and pregnancy diagnosis group based on the initial diagnosis time. Then in the pregnancy diagnosis group, the cases diagnosed before 24 gestational weeks were defined as group A, and those diagnosed at or after 24 gestational weeks were defined as Group B. Maternal and pregnancy variables, as well as pregnancy outcomes, including delivery age of pregnant women, the rate of pregnancy loss, delivery gestational weeks, neonatal birth weight, the proportion of insulin treatment, the rate of pre-term, macrosomia, newborns transferred to pediatrics, the average of HbA1c level, and preeclampsia, were analyzed among groups by paired Student’s t-test. Results: The rate of missed diagnosis before pregnancy was 68.1%. The proportion of insulin treatment and the rate of the cesarean section had a significant difference between pre-pregnancy diagnosis group and pregnancy diagnosis group. The characteristics and pregnancy outcomes in pregnancy diagnosis group A were not significantly different from those in the pre-pregnancy diagnosis group. However, in the pregnancy diagnosis group B, the proportion of pregnant women using insulin treatment and the average HbA1c level had a statistically significant difference, compared to pregnancy diagnosis group A, as well as the pre-pregnancy group. Conclusions: The rate of undiagnosed PGDM was high, and PGDM was significantly associated with multiple adverse pregnancy outcomes. Fasting plasma glucose should be used as a screening test to identify PGDM at pre-pregnancy or first antenatal care.