Heterogeneity of insulin resistance and beta cell dysfunction in gestational diabetes mellitus: a prospective cohort study of perinatal outcomes.

BACKGROUND: Insulin resistance and beta cell dysfunction were reported to be responsible for gestational diabetes mellitus (GDM). However, little is known about the heterogeneity of these factors and its influences on perinatal outcomes. We investigated whether subtypes of insulin resistance and beta cell dysfunction in gestational diabetes mellitus have different impacts on perinatal outcomes. METHODS: In this prospective cohort study, we followed 554 pregnant women and glucose challenge test was performed at 24-28th weeks of their gestation. Women with plasma glucose ≥ 7.8 mmol/L would be included and advised to undergo the diagnostic 75-g, 3-h oral glucose tolerance test. According to indices of measuring insulin resistance or beta cell function were below the 25th percentile of women with normal glucose tolerance (NGT), women with GDM were defined as three subtypes: GDM with the beta cell dysfunction, GDM with the insulin resistance defect or GDM with both traits mentioned above (GDM-mixed). Perinatal outcomes were documented. RESULTS: The levels of prepregnancy and maternal BMI in the GDM-mix group were higher compared to women in the NGT group (23.2 ± 4.0 vs 20.8 ± 3.7 kg/m2, P < 0.001; 24.5 ± 4.3 vs 21.8 ± 3.4 kg/m2, P < 0.001, respectively). Furthermore, women in GDM-mix group more likely to be subjected to LGA (P = 0.008) adverse perinatal outcomes (P = 0.005), although these differences were normalized after adjusting age, prepregnancy and maternal BMI (GDM-mix vs. NGT: P = 0.141 for LGA and P = 0.186 for adverse outcomes). On the other hand, all perinatal outcomes were similar between other two GDM subgroups and NGT group. CONCLUSIONS: Women with GDM display respective characteristics on metabolism disorders and confer discriminating risks of adverse perinatal outcomes because of this heterogeneity.