Human placental glucose uptake and transport are not altered by the oral antihyperglycemic agent metformin

OBJECTIVE: Our purpose was to determine whether the biguanide oral antihyperglycemic agent metformin increases human placental uptake and transport of glucose to the fetal circulation. STUDY DESIGN: The human single-cotyledon model was used to compare transport of tritiated glucose in the maternal to fetal direction in eight human placentas between control placentas and those exposed to metformin in vitro. Transport was calculated from the serial perfusate glucose levels obtained in each 3-hour experiment, and placental uptake was determined from homogenates of the perfused cotyledon. Liquid scintillation spectrometry measured levels of both glucose and the reference substance antipyrine. Transport was compared by the Mann-Whitney U test. RESULTS: Mean maternal and fetal glucose levels were 77.5 +/- 4.9 mg/dl and 61.3 +/- 5.9 mg/dl, respectively, in the metformin group and 83.8 +/- 4.3 mg/dl and 60.4 +/- 12.4 mg/dl, respectively, in controls at 2 hours. Placental glucose uptake was 91.1 +/- 42.2 mu g/gm placenta in the metformin experiments and 104.9 +/- 76.9 mu g/gm placenta in controls. No difference in placental glucose uptake or transport could be demonstrated. CONCLUSION: Metformin does, not affect human placental glucose uptake or transport.