Placental glucose transport in gestational diabetes mellitus

OBJECTIVE: We have previously reported that type 1 diabetes mellitus with hyperglycemia during the first trimester is associated with an up-regulation of placental glucose transport at term. We speculated that glucose concentrations regulate placental glucose transporters only during early pregnancy. To test this hypothesis we studied placental glucose transport in gestational diabetes mellitus, which is associated with hyperglycemia mainly during the second half of pregnancy. STUDY DESIGN: Syncytiotrophoblast microvillous membrane vesicles and basal membrane vesicles were isolated from uneventful pregnancies (control group, n = 32) and pregnancies complicated by gestational diabetes mellitus (n = 18). Glucose uptake and glucose transporter 1 expression were studied by means of radiolabeled tracers and Western blotting, respectively. RESULTS: Gestational diabetes mellitus was not associated with alterations in placental glucose transport. Separate analysis of 6 patients in the gestational diabetes mellitus group with large-for-gestational-age babies did not affect these results. CONCLUSION: These findings are consistent with the hypothesis that the sensitivity of placental glucose transporters to regulation by nutrient availability is limited to early pregnancy.