A new classification method for gestational diabetes mellitus: a study on the relationship between abnormal blood glucose values at different time points in oral glucose tolerance test and adverse maternal and neonatal outcomes in pregnant women with gestational diabetes mellitus

Background

Gestational diabetes mellitus (GDM) can lead to various adverse pregnancy outcomes for both mothers and infants, including gestational hypertension, premature rupture of membranes, preterm birth, macrosomia, large for gestational age (LGA) infants, and neonatal hypoglycemia. Previous studies have mainly focused on the overall risk of GDM for adverse maternal and neonatal outcomes, but there has been limited research specifically investigating the relationship between different patterns of abnormal oral glucose tolerance test (OGTT) results and adverse maternal and neonatal outcomes.

Objective

The study aimed to analyze the maternal and neonatal outcomes among GDM women with different OGTT patterns and to explore a new classification method capable of stratifying GDM into high-risk (GDM-HR) and low-risk subtypes based on OGTT results.

Study Design

We conducted a retrospective cohort study at the Women's Hospital, School of Medicine, Zhejiang University, spanning from November 1, 2015, to April 30, 2018. During the study period, a total of 3268 cases of GDM were enrolled. Based on the results of the OGTT, these GDM cases were classified into 7 subtypes, and the composition ratio of each subtype and their maternal and neonatal outcomes were analyzed. Innovatively, we proposed to categorize GDM-HR (characterized by elevated fasting blood glucose [FBG] levels, including T0, T0+1, T0+2, and T0+1+2) and low-risk GDM (GDM-LR, without elevated FBG, including T1, T2, and T1+2) and compared the maternal and neonatal outcomes between the two subtypes.

Results

(1) In this cohort of 3268 GDM cases, the composition ratios of the 7 GDM subtypes were as follows: T0 (7.9%, n=260), T1 (24.2%, n=791), T2 (27.4%, n=897), T0+1 (5.4%, n=175), T0+2 (1.7%, n=56), T1+2 (26.2%, n=855), and T0+1+2 (7.2%, n=234). (2) GDM subtypes with elevated FBG levels (GDM-HR) exhibit more severe adverse prognostic outcomes compared to those without elevated FBG levels (GDM-LR). (3) Multiple logistic regression analysis revealed that compared to the GDM-LR group, the GDM-HR group showed increased fetal birth weight (by approximately 150 grams), and had higher rates of cesarean section (adjusted odds ratio [aOR]: 1.45, 95% confidence interval [CI]: 1.19–1.76), hypertensive disorders of pregnancy (aOR: 1.78, 95% CI: 1.35–2.35), preterm birth (aOR: 1.59, 95% CI: 1.17–2.16), macrosomia (aOR: 2.66, 95% CI: 2.07–3.43), LGA infants (aOR: 2.46, 95% CI: 2.05–2.97), and neonatal hypoglycemia (aOR: 2.00, 95% CI: 1.37–2.91). Partial correlation analysis shows a positive correlation between fetal birth weight and FBG levels, with r=0.222, P<.001. Multiple linear regression indicates that for every 1 mmol/L increase in FBG, the fetal weight is estimated to increase by approximately 188 grams.

Conclusion

The composition ratio of GDM subtypes with elevated FBG (GDM-HR) is relatively low within GDM cases, yet it presents with a higher risk of adverse outcomes compared to subtypes without elevated FBG (GDM-LR), warranting increased attention from obstetricians. Applying this new classification method in clinical practice enables better differentiation and individualized management of GDM.