Early gestational diabetes mellitus and type 2 diabetes: do they differ in perinatal outcome– a retrospective analysis

The rise in type 2 diabetes (T2D) during pregnancy is mainly due to increasing obesity and metabolic disorders. Early gestational diabetes mellitus (eGDM), diagnosed before 20 weeks, is also becoming more common and often may explain underlying metabolic problems. This study compares perinatal and neonatal outcomes in patients with T2D and eGDM. This retrospective study included 141 pregnant women (70 with T2D and 71 with eGDM) and their singleton term neonates born between 2020 and 2025. The women attended at least one follow-up visit per trimester. eGDM was diagnosed before 20 weeks of gestation based on an oral 75 g glucose tolerance test according to Polish recommendations. Each patient had their HbA1c levels measured at the time of diagnosis and then in each trimester of pregnancy. As a comparator, we used our university hospital growth charts and calculated neonatal growth data from healthy women who delivered at the same hospital between 2017 and 2022. Statistical analysis was performed using PQStat, with p-values < 0.05 considered statistically significant. Pre-pregnancy obesity was more common in the eGDM group (94.4% vs. 77.1%,p < 0.05). Women with T2D gained more weight (p < 0.005) and had higher HbA1c levels throughout pregnancy (p < 0.005) than those with eGDM. Insulin was required more often in women with T2D (98.6% vs. 63.4%, p < 0.05) and started earlier in T2D (9 vs. 15 weeks, p < 0.005). Preterm birth rates were similar in the T2D and eGDM groups 12.7% vs. 15.7%), as were cesarean section rates (62.9% vs. 60.6%), LGA (15.7% vs. 26.8% according to local growth charts) and SGA (20% vs. 26.8% according to local growth charts). Neonatal jaundice was less frequent in the T2D group (21.4% vs. 36.8%, p < 0.05). Congenital defects occurred at a similar frequency in both groups (T2D: 5.6% vs. eGDM: 8.6%). The study groups differed significantly in weight gain during pregnancy, the need for and onset of insulin administration, and the incidence of jaundice in newborns. Prepregnancy obesity in the eGDM group may be the main factor predisposing to the trend to a higher percentage of LGA babies in this group. The frequency of congenital malformations in both groups reinforces the need for pre-conception counselling for their prevention.