Comparison of HbA1c and Time in Range in the Prediction of Large for Gestational Age in Pregnancies Involving Type 1 Diabetes.

Background/

Objectives

While satisfactory glycaemic control is possible with specialist care from a diabetologist and modern therapies, women with type 1 diabetes are still subject to poorer obstetric outcomes, even with optimal management.

Methods

The analysis comprised a cohort of 55 pregnant patients with type 1 diabetes who attended the Diabetology Outpatient Clinic between 2018 and 2023; all were recruited no later than the first trimester. Qualified patients underwent medical interviews and physical examinations. Insulin pump, continuous glucose monitoring (CGM) system, and postpartum data were collected.

Results

The median glycated haemoglobin (HbA1c) at the beginning of pregnancy was 6.1%, with means of 5.9% and 6.0% in the following trimesters. Only 1/3 of the women achieved the recommended HbA1c value throughout pregnancy. The average/median time in range (TIR) in each trimester was ≤70%. Among the women who achieved the recommended TIR target, the infants tended to have lower birth weights but a higher likelihood of jaundice. Almost half of the newborns were large for gestational age (LGA), and a third were macrosomic. The strongest predictor of LGA was a mean blood glucose level > 124 mg/dL in the third trimester, which increased the risk of LGA by almost 12 times.

Conclusions

Good diabetes control does not prevent LGA/macrosomia. TIR appears to be a better predictor of obstetric complications, including LGA. A mean glucose level ≥ 124 mg/dL in the third trimester greatly increases the risk of LGA.