Placental glucose transport and utilisation is altered at term in insulin-treated, gestational-diabetic patients

We have previously shown that placentae from patients with gestational diabetes mellitus who did not receive insulin had lower glucose transport and utilisation than non-diabetic control subjects. To assess the placental glucose handling characteristics of women with gestational diabetes mellitus receiving insulin, we examined glucose transport and utilisation in placentae from three groups of women after term delivery: those with gestational diabetes mellitus and receiving insulin (n = 9, insulin group); those with gestational diabetes mellitus and not receiving insulin (n = 10, no insulin group); and those with normal, non-diabetic pregnancies (n = 9, control group).

Dual perfusion of an isolated placental lobule was done using maternal glucose concentrations of 4, 8, 16 and 24 mmol/l. Glucose and L-lactate concentrations in the maternal and fetal effluents were measured. Direct glucose transfer from the maternal to the fetal effluent was measured using 14C-D-glucose. Mean rates in micromol ming(-1) (wet tissue) at maternal glucose concentration of 8 mmol/l are shown.

Glucose uptake from the maternal perfusate (insulin group 0.57, no insulin group 0.30) and net glucose transfer to the fetal effluent (insulin group 0.41, no insulin group 0.20) both increased in the placentae of women receiving insulin compared with the diabetic group not receiving insulin. Both groups of patients had lower placental glucose utilisation than the control group (insulin group 0.16, no insulin group 0.10, control group 0.25).

These results suggest that materno-fetal glucose transport increases in the placentae of women with gestational diabetes mellitus who receive insulin compared with those women who do not receive insulin.