MEASUREMENT OF GLUCOSE-METABOLISM AND INSULIN-SECRETION DURING NORMAL-PREGNANCY AND PREGNANCY COMPLICATED BY GESTATIONAL DIABETES

Gestational diabetes affects 2-3% of pregnant women and is associated with foetal complications including macrosomia and an increased likeli hood of developing diabetes in later life. We have therefore studied s even women with gestational diabetes and five control women both durin g the third trimester of pregnancy and again 2-3 months postpartum, us ing the minimal model analysis of the frequently sampled labelled ([6, 6-H-2(2)]-glucose) intravenous glucose tolerance test. Glucose tolera nce (glucose K-d) was significantly reduced in the women with gestatio nal diabetes compared with the normal pregnant women both in pregnancy (1.16 +/- 0.11 vs 1.78 +/- 0.23 %/min; p < 0.05) and post-partum (1.4 7 +/- 0.22 vs 2.59 +/- 0.43 %/min;p < 0.05) and increased significantl y in the control women after delivery (p)< 0.05). Glucose effectivenes s was not significantly different between the women with gestational d iabetes and the control group either during or after pregnancy. Insuli n sensitivity was significantly lower during pregnancy than after deli very in the women with gestational diabetes (p < 0.05). There was no s ignificant difference in basal insulin secretion in the two groups dur ing pregnancy or post-partum However, during pregnancy the control sub jects significantly increased (p < 0.001) their insulin secretion over a period of 20 min in response to an Intravenous glucose tolerance te st (96.2 +/- 42.7 pmol/kg) compared with post-partum values (58.3 +/- 25.2 pmol/kg) while in the women with gestational diabetes insulin sec retion was similar in pregnancy (65.5 +/- 9.3 pmol/kg) and after deliv ery (57.7 +/- 15.7 pmol/kg). These data suggest that the glucose intol erance in gestational diabetes compared to normal pregnancy is due to reduced insulin sensitivity and an impaired ability in gestational dia betes to increase insulin secretion in response to glucose.