Comparative Analysis of Perinatal Outcomes in Type 1 and Type 2 Diabetes Pregnancies: A Retrospective Study

The prevalence of type 1 (T1D) and type 2 (T2D) diabetes in reproductive women is rising. Subclinical hyperglycemia's impact on adverse pregnancy outcomes is evident. Nevertheless, the variance in outcomes between T1D and T2D pregnancies is not well-defined. We retrospectively analyzed 68 pregnancies (28 T1D, 40 T2D) at the Gunma University Hospital (Dec 2017-Mar 2022), examining maternal characteristics, insulin therapy, prepregnancy body mass index (BMI), glycated hemoglobin (HbA1c) levels, daily insulin dose, gestational weight gain, and perinatal outcomes. In T1D pregnancies, those with large-for-gestational age (LGA) infants had less improvement in HbA1c early in pregnancy and greater weight gain overall. Notably, even non-obese women with T1D often gained excessive weight, which was closely tied to LGA risk. The risk increased sharply when third-trimester HbA1c exceeded 48 mmol/mol (6.5%). These findings suggest that, despite significant gestational weight gain, insulin doses may not have been sufficiently escalated to match increased insulin resistance, contributing to both poor glycemic control and a higher risk of LGA in T1D pregnancies. Our study underscores the importance of tailoring insulin therapy and weight management to reduce LGA risk in T1D. As the use of advanced technologies such as continuous glucose monitoring (CGM), continuous subcutaneous insulin infusion (CSII), and sensor-augmented pump (SAP) therapy continues to expand in pregnancy care, ongoing data updates will be essential to refine clinical strategies and improve maternal and neonatal outcomes.