Patterns of insulin, growth hormone, and placental lactogen release after protein and glucose-protein ingestion in pregnancy

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.

Endocrine-metabolic response to acute starvation in human gestation

During a 72 hour fast in pregnant women, significant decrements in the maternal plasma glucose concentrations, accompanied by a significant increase in the plasma placental lactogen (hPL) concentration, occur. At the same time, utilization of glucogenic amino acids, principally alanine, takes place. The mean postprandial glucose concentration in pregnancy is significantly lower than that of comparable nonpregnant women (70.5 +/- 1.7 versus 79.5 +/- 1.3 mg. per 100 ml., p less than 0.001). There appears to be a significant sparing effect on the maternal plasma glucose concentration during acute fasting which may be mediated through hPL. Concentrations of amniotic fluid and fetal plasma glucose from women undergoing fasting decrease in a manner parallel to that of the mother. Fasting provokes a mean rise in plasma hPL of 33.2 per cent over basal levels. This rise is still evident 72 hours after refeeding, after which it gradually returns to pretest concentrations. The infusion of alanine or arginine to pregnant women at the end of the fast produced increments in the peripheral maternal glucose concentration. The response was much greater with alanine than with arginine, demonstrating the increased gluconeogenic potential of this amino acid. The increment in human growth hormone (hGH) following alanine infusion was significantly greater than that observed after arginine administration. Hypoaminoacidemia was present in nonpregnant and pregnant women in response to fasting, but the decline was greater in pregnancy. Acute fasting in the first half of gestation appears to produce significant alterations in carbohydrate metabolism evidenced by profound hypoglycemia, hypoinsulinemia, and hypoaminoacidemia. This maternal deficit can be reflected in fetal substrate concentrations. The effect of these changes on fetal growth and development is speculative at this time.

Gestational and pregestational diabetes: an approach to therapy

The objective of management in the pregnant diabetic patient is to achieve physiologic glucose homeostasis through the use of diet and insulin. As outlined, the numerous ancillary tests developed during the past 15 years to assist the clinician in determining impending fetal death have left much to be desired, especially where metabolic homeostasis has not been achieved prior to the thirty-sixth week of gestation. The statistics from this institution indicate that the maintenance of the plasma glucose concentration below 100 mg. per cent throughout gestation, regardless of the severity of the diabetes, all but removes the risk of maternal-fetal complications due to diabetes. The management is uniform for all patients exhibiting an abnormality of carbohydrate metabolism, and, although it is rather difficult to accept, there have been minimal neonatal complications when the protocol outlined in this presentation has been followed.