The insulin response to glucose infusion in normal human pregnancy
Using a glucose infusion test insulin responses and insulin sensitivities were studied in 15 gestational diabetic women at 36–40 weeks gestation. In all women intravenous glucose tolerance had returned to normal at six weeks postpartum. Twelve women had a repeat glucose infusion test done 7–24 weeks (mean 17 weeks) postpartum. The results were compared with previously evaluated normal non-pregnant and normal pregnant standards and insulin responses below the normal 15th percentile were defined as “low”. Twelve women had “low” insulin responses in late pregnancy, and six had “low” insulin responses postpartum. The mean insulin sensitivity index of 1.34±1.21 (mean ±SD) was significantly higher in the gestational diabetic group during pregnancy compared with a control pregnant group at 0.53±0.21 (p<0.01). The findings in this study support the hypothesis that gestational diabetes may arise in women who are unable to achieve adequate insulinogenic compensation to pregnancy. Increased insulin sensitivity in gestational diabetes may be a compensatory mechanism.