Heterogeneity of gestational diabetes and risk for adverse pregnancy outcome: a cohort study.

Context: Diabetes has increasingly been recognized as a heterogeneous disease, with clinical characteristics and outcomes risk varying across different phenotypes. Evidence on heterogeneity of gestational diabetes (GDM) is yet to be provided.

Objective: To investigate the insulin physiology and pregnancy outcomes of GDM phenotypes characterized by fasting hyperglycemia or postload hyperglycemia.

Methods: A total of 2050 women who underwent a 75-g oral glucose tolerance test were prospectively recruited and followed up until delivery. Women were categorized into normoglycemia (NGT, n = 936), isolated impaired fasting glucose (gestational-IFG, n = 378), and isolated impaired postload glucose tolerance (gestational-IGT, n = 736) groups. Fasting blood sample at mid-pregnancy were collected to measure C-peptide and insulin concentrations. Homeostasis model assessment (HOMA) and quantitative insulin sensitivity check index (QUICKI) were used to evaluate insulin physiology. Maternal and neonatal outcomes were recorded.

Results: Gestational-IFG had greater insulin resistance (HOMA-IR 3.11 vs. 2.25, QUICKI-CP 0.94 vs. 1.03, both P < 0.01), and gestational-IGT had worse β-cell function (C-peptide 2.00 vs. 2.26 ng/ml, P < 0.05) when compared to one another. Gestational-IFG was more strongly associated with excessive gestational weight gain (RR 1.62, 95% CI 1.18-2.23) and large-for-gestational-age infants (RR 1.45, 95% CI 1.03-2.03) than gestational-IGT. The risk for neonatal brain injury was increased in gestational-IGT (RR 2.03, 95% CI 1.04-4.09), but not in gestational-IFG (P = 0.439). Gestational-IGT showed a stronger association with the risk of preterm birth compared to gestational-IFG (RR 1.80, 95% CI 1.02-3.36).

Conclusion: GDM exhibits distinct insulin physiology profiles. Pregnancy outcome varies between each phenotype. These findings provide evidence on risk stratification and diverse strategies for the treatment of GDM.