Fetal proinsulin and insulin and placental weight in pregnancies complicated by gestational diabetes and obesity

A. J. Marin, C. I. Tirgoviste

Abstract: We evaluated the role of fetal proinsulin and insulin on placental weight in patients with gestational diabetes. We investigated a group of 15 patients diagnosed with gestational diabetes and 24 patients without diabetes. All cases of gestational diabetes during pregnancy found did not require insulin therapy. Were analyzed patient’s age, parity, gestational age, sex and birthweight, Apgar score, placental weight immediately after birth, fetoplacentar index (weight divided by placental weight of the child), maternal weight and body mass index before pregnancy, blood pressure, and presence of metabolic syndrome. In addition were analyzed maternal glucose, total cholesterol, and triglycerides in the first trimester and proinsulin and insulin in cord blood at birth. Fetal insulin and proinsulin showed significantly higher values in the group with diabetes compared to controls - Insulin 40.5 pmol /l (17.9-64.5) vs 81.3 pmol/l (53-121), p <0.001 and 7.73 pmol/l proinsulin (5-13) vs 13.3 pmol/l (8-23 ), p <0.001). The proinsulin/ insulin ratio was similar in both groups. Placenta is heavier in diabetic patients (686 g ± 77 vs 565 g ± 83 p <0.001), but fetoplacentar index showed no statistically differences in patients with gestational diabetes. Statistical analysis revealed the linear relationship of glucose with the fetal weight, placental weight and with the fetal proinsulin and insulin. Finally, fetal proinsulin and insulin are both increased in the same time with placental weight. The proinsulin/placental and insulin/placental ratios did not differ between studied groups, these hormones being in direct relationship with placental weight. Umbilical cord proinsulin and insulin levels are elaveted at birth in neonates from diabetic mothers. The fetal pronsulin/insulin ration could be a better marker of pancreatic beta cell function. Placental weight is increased in diabetic patients in relationship with hyperglycemia, and the present study showed a direct relationship of placental weight and fetal insulinemia and proinsulinemia.
Keywords: insulin, proinsulin, fetal pancreatic beta cells, placenta, umbilical cord, obesity, diabetes, apoptosis