Human placental lactogen concentration during physiological fluctuations of serum glucose in normal pregnant and gestational diabetic women

Evaluation of Circulating Determinants of Beta-Cell Function in Women With and Without Gestational Diabetes

CONTEXT

Gestational diabetes (GDM) arises in women in whom there is insufficient β-cell compensation for the insulin resistance of late pregnancy. The mechanisms underlying both normal antepartum β-cell adaptation and its aberrancy in GDM are unclear. Preclinical studies have suggested that the hormones prolactin and human placental lactogen (HPL) may stimulate β-cell mass, whereas the furan fatty acid metabolite 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF) has recently emerged as a potential negative regulator of β-cell function. However, there has been limited study of these factors in humans.

OBJECTIVE

Our objective was to systematically evaluate HPL, prolactin, and CMPF in relation to glucose homeostasis and β-cell function in women with and without GDM.

DESIGN/SETTING/PARTICIPANTS

Three-hundred-and-ninety-five women underwent an oral glucose tolerance test in late pregnancy, enabling assessment of GDM status, glycemia (area-under-the-glucose-curve on oral glucose tolerance test [AUCglucose]), β-cell function (Insulin Secretion-Sensitivity Index-2, insulinogenic index/homeostatic model assessment of insulin resistance [HOMA-IR]), insulin sensitivity/resistance (Matsuda index, HOMA-IR), and circulating HPL, prolactin, and CMPF.

RESULTS

Serum concentrations of HPL, prolactin, and CMPF were similar between women with GDM (n = 105) and women without GDM (n = 290). However, on multiple linear regression analyses, CMPF emerged as a significant predictor of AUCglucose in women with GDM (t = 4.75, P < .0001) but not in their peers (P = .60). Furthermore, CMPF independently predicted lower Insulin Secretion-Sensitivity Index-2 (t = -2.28, P = .02) and lower insulinogenic index/HOMA-IR (t = -2.22, P = .03) in women with GDM but not in the non-GDM group (both P = .93). Neither HPL nor prolactin was significantly associated with AUCglucose, β-cell function, or insulin sensitivity.

CONCLUSION

CMPF is a potential circulating determinant of β-cell dysfunction and hyperglycemia in women with GDM.

Placental lactogen, progesterone, total estriol and prolactin plasma levels in pregnant women with insulin-dependent diabetes mellitus

Fifteen insulin-dependent diabetic (White's class B-C) and 10 healthy pregnant women were examined from the 12th to the 36th wk. Every 4 wk, a blood sample was drawn to determine total estriol, progesterone, placental lactogen and prolactin. Throughout the pregnancy, total estriol and progesterone in diabetic and non-diabetic women are very similar. On the contrary, the PRL levels are constantly lower in diabetic pregnant women, even though the difference is statistically significant only for the 24th wk determination. The hPL level is instead significantly lower in diabetic pregnant women at the 12th, 20th, 24th, 32nd and 36th wk. A negative correlation exists between the hPL value and the mean blood glucose level, performed the same day as the hormonal test. This correlation is statistically significant at the 12th, 16th, 20th, 28th and 36th wk. No significant difference is found between the two groups examined for the delivery week, the placental weight, the birth weight and the fetal body weight index. To conclude, while estriol and progesterone are not affected by the higher variability of glucose levels during pregnancy in diabetics, compared to normals, hPL and perhaps also PRL may be influenced by the mild hyperglycemia consequent to diabetes.

Absence of human placental lactogen in an otherwise uneventful pregnancy

Human placental lactogen (hPL) is commonly used in surveying the placental function during normal and pathologic pregnancies. This report describes a pregnancy where hPL could not be found in maternal serum or placental tissue. The pregnancy was in all other respects completely normal, ending with the birth of a normal baby. Some possible reasons and consequences of this unique event are discussed.

Plasma human placental lactogen profiles over 24 hours in normal and diabetic pregnancy

Plasma human placental lactogen (HPL) concentrations have been measured at frequent intervals over 24 hours in 24 normal women, 13 chemical and 13 insulin dependent diabetic patients during the third trimester of pregnancy. Most of the women studied displayed variation in HPL levels during the day, but there was no evidence of a diurnal rhythm, nor significant changes following meals or during the nocturnal fast. The mean plasma HPL concentrations over 24 hours in the chemical and insulin dependent diabetic patients (5-9+/-SD 1-3 and 5-9+/-1-7 microng/ml respectively) were greater than those in normal women (5-1+/-1-2 microng/ml) but this difference was not significant. No significant change in plasma HPL concentrations was observed during a five-hour oral glucose tolerance test in either the normal or chemical diabetic group. It is suggested that in normal pregnant women HPL does not itself contribute to glucose homeostasis but acts as a 'regulator' which alters the actions of certain maternal hormones to achieve a favourable environment for fetal growth.