Placental lactogen, placental growth factor, insulin resistance in early pregnancy and risk for gestational diabetes

Abstract

Background and aims. Placental hormones and proteins are important regulators of insulin resistance during pregnancy. However, the data concerning the assosiation between placental lactogen (PL) and placental growth factor (PLGF) level in early pregnancy and further development of gestational diabetes mellitus (GDM) are limited and incostintent. The aim of this study was to compare the level of these two placental proteins and homeostasis model assessment of insulin resistance (HOMA-IR) in early pregnancy among women diagnosed with and without GDM months later.Materials and methods. A nested case-control study was conducted in a prospective cohort of pregnant women. Among them, 78 incident GDM cases were identified and 95 women who were not diagnosed with GDM were randomly selected as a control group. Blood was sampled for measurements of PL, PLGF, fasting plasma glucose and insulin at 8-14 weeks of pregnancy. All the women underwent oral glucose tolerance test (OGTT) at 24-32 weeks. GDM was diagnosed according to the International Association of Diabetes In Pregnancy Study Groups (IADPSG) recommendations (fasting glucose ≥5.1 mmol / l and / or 1 hour ≥10.0 mmol / l and / or 2 hours ≥8.5 mmol / L). The maternal and neonatal anthropometric parameters were also measured. Statistical analysis included Student's t-test, logistic regression and Pearson's correlation.Results. There was no difference between GDM and control groups in the mean levels of PL (0,70 +/- 0,53 vs 0,81 +/- 0,58 mg/L, р =0,215 ) and PLGF (60,7 +/- 169.6 vs 46,6+105,6 pg/ml, р=0,503). Women with GDM were older (30.2 +/- 3.9 vs 28.4 +/- 4.7 years, p = 0.008), had higher first trimester body mass index (BMI) (25.2 +/- 5.2 vs 23.1 +/- 4.6 kg/m2, р = 0.006), higher levels of insulin (10.3 +/- 5.5 vs 7.9 +/- 3.9 mU/L, p = 0,007) and HOMA-IR ( 2.17 +/- 1.1 vs 1.7 +/- 0.9, p = 0,007) compared to the control group. Women with GDM also had a higher level of fasting plasma glucose (4.8 + 0.6 and 4.6 + 0,5 mmol/L, p = 0.063), although the difference did not reach statistical significance. HOMA-IR was positively associated with the development of GDM (OR: 1.62, 95% CI: 1.12 - 2.34, P = 0.01) and the association retained under a multivariable analysis controlling for age and BMI (OR: 1.59, 95% CI: 1.04 - 2.45, P = 0.033). Maternal PL and PLGF were not related to the results of OGTT, HOMA-IR or neonatal anthropometry. A positive correlation between PL level and gestational age at the time of blood sampling was observed (r = 0.657, p <0.001).Conclusion. Serum concentrations of PL and PLGF in pregnant women at 8-14 weeks’ gestation were not associated with HOMA-IR and later development of GDM. Higher HOMA-IR score in early pregnancy is significantly associated with an elevated risk for GDM.