Higher Fetal Insulin Resistance in Chinese Pregnant Women with Gestational Diabetes Mellitus and Correlation with Maternal Insulin Resistance

OBJECTIVE: The aim of this study was to determine the effect of gestational diabetes mellitus (GDM) on fetal insulin resistance or β-cell function in Chinese pregnant women with GDM. MEASUREMENTS: Maternal fasting blood and venous cord blood samples (reflecting fetal condition) were collected in 65 well-controlled Chinese GDM mothers (only given dietary intervention) and 83 control subjects. The insulin, glucose and proinsulin concentrations of both maternal and cord blood samples were measured, and the homeostasis model assessment of insulin resistance (HOMA-IR) and the proinsulin-to-insulin ratios (an indicator of fetal β-cell function) were calculated in maternal and cord blood respectively. RESULTS: Both maternal and fetal levels of insulin, proinsulin and HOMA-IR but not proinsulin-to-insulin ratios were significantly higher in the GDM group than in the control group (maternal insulin, 24.8 vs. 15.4 µU/mL, P = 0.004, proinsulin, 23.3 vs. 16.2 pmol/L, P = 0.005, and HOMA-IR, 5.5 vs. 3.5, P = 0.041, respectively; fetal: insulin, 15.1 vs. 7.9 µU/mL, P<0.001, proinsulin, 25.8 vs. 15.1 pmol/L, P = 0.015, and HOMA-IR, 2.8 vs. 1.4, P = 0.017, respectively). Fetal HOMA-IR but not proinsulin-to-insulin ratios was significantly correlated to maternal HOMA-IR (r = 0.307, P = 0.019), in the pregnant women with GDM. CONCLUSIONS: Fetal insulin resistance was higher in Chinese pregnant women with GDM than control subjects, and correlated with maternal insulin resistance.