Human placental insulin binding in normal and well-controlled diabetic patients

Previous studies of insulin binding to placentas of both insulin-dependent and untreated gestational diabetic patients have described placentas from diabetics to contain fewer insulin receptors than placentas from nondiabetic gravidas. However, these studies were done using membrane fractions prepared from the placentas and at a time when adequacy of the antepartum glycemic control in the diabetic patients was not routinely evaluated by self blood sugar measurement of hemoglobin A₁ assay. The current study compares specific ¹²⁵I-insulin binding in vitro to intact placental villi from 15 normal patients with insulin binding to intact villi obtained from 15 insulin-dependent diabetic mothers whose fasting and postprandial blood sugars and hemoglobin A₁ levels were maintained in a range normal for term pregnancy. We demonstrate that insulin binding to intact placental villi is the same in this group of diabetic patients as in the nondiabetic patients.