Characteristics and pregnancy outcomes of subtypes of gestational diabetes mellitus based on HOMA-IR and BMI.

AIM

To identify the characteristics and pregnancy outcomes across different subgroups of gestational diabetes mellitus (GDM) categorized by insulin resistance index and body mass index (BMI) in early pregnancy.

METHODS

This retrospective study included 1804 women who underwent a 75 g-OGTT during 22-28 weeks of gestation, categorized into normal glucose tolerance (NGT) (1487) and GDM (317 [17.57%] of the total cohort). Metabolic parameters were assessed, and equation of homeostatic model assessment (HOMA) were utilized to compute indices of insulin resistance (HOMA-IR), β-cell secretory (HOMA-B), and insulin sensitivity (HOMA-%S) in early and mid-pregnancy. The cut-off value of HOMA-IR (1.61) in early pregnancy was determined via ROC curve analysis. This value, combined with pre-pregnancy BMI, further categorized NGT and GDM into six subgroups respectively, based on HOMA-IR levels (≥ 1.61 or < 1.61) and BMI categories (< 18.5 kg/m, 18.5-25 kg/m, or ≥ 25 kg/m).

RESULTS

In comparison to women with NGT, those with GDM were notably older, had higher pre-BMI, fasting plasma glucose (FPG), insulin, and lipid levels in early pregnancy. They also exhibited more pronounced insulin resistance in both early and mid-pregnancy, leading to poorer outcomes. Following an oral glucose load, the peaks of glucose and insulin were out of sync in GDM and its subgroups, accompanied by further increases in HOMA-IR, HOMA-B, and a decrease in HOMA-%S, except for the GDM subgroup with HOMA-IR < 1.61/BMI < 18.5 kg/m. Conversely, glucose and insulin secretion in NGT and its subgroups peaked synchronously at 60 min. GDM women with HOMA-IR ≥ 1.61/18.5 kg/m ≤ BMI < 25 kg/m had higher rates of neonatal jaundice (34.5% vs 13.9%, p < 0.0001), LGA (28.9% vs 13.2%, p = 0.001), macrosomia (9.8% vs 3.7%, p = 0.025) compared to peers, while in GDM women with HOMA-IR ≥ 1.61/BMI ≥ 25 kg/m, the rates of LGA and macrosomia were 26.6% and 8.4%, respectively. The GDM subgroup with HOMA-IR < 1.61/BMI < 18.5 kg/m exhibited the highest rates of premature rupture of membrane (46.7%) and postpartum hemorrhage (20%), predominantly with vaginal delivery and a 1 min Apgar score of 4.5% in GDM women with HOMA-IR < 1.61/18.5 kg/m ≤ BMI < 25 kg/m.

CONCLUSION

GDM and its subgroups displayed severe insulin resistance and poorer insulin sensitivity, leading to an increased risk of adverse pregnancy outcomes. GDM women with higher IR and normal or over weight were more likely to experience LGA and macrosomia, while those with lower IR and underweight were prone to premature rupture of membrane and postpartum hemorrhage during vaginal delivery.