Amniotic Fluid C-peptide Research Articles

Maternal Glucose Metabolism and Amniotic Fluid C-Peptide Levels as Measures of Intrauterine Fetal Growth.

Maternal fasting blood glucose, glucose tolerance and amniotic fluid C-peptide levels can be useful for detecting intrauterine growth retardation prior to birth.

Fatty acid composition of amniotic fluid lecithin and its relationship to amniotic fluid C-peptide in diabetic pregnancy.

Fatty acid composition in lecithin and C-peptide was analysed in amniotic fluid samples obtained from 28 normal and 24 insulin-treated diabetic women in the 34th to 39th week of pregnancy. The pattern of changes of fatty acid composition of amniotic fluid (AF) lecithin was essentially the same in pregnancies complicated by diabetes as in non-diabetic controls. However, at 36/37 weeks, the mean values for palmitoleic acid (16:1) were statistically higher in diabetic women (P less than 0.02), and the mean values for stearic acid (18:0) were higher for normals (P less than 0.02). The mean C-peptide value was more than twice as high (0.71 nmol/l) in the diabetic group than in the control group (P less than 0.01). The lecithin/sphingomyelin (L/S) and palmitic/stearic acid (P/S) ratios were equal in both groups. Neither in five diabetic patients with fetuses indicating marked hyperinsulinism (C-peptide greater than 1.0 nmol/l) nor in the remaining group of patients was there any relationship between C-peptide levels and the lecithin fatty acid composition.

Good diabetic control early in pregnancy and favorable fetal outcome : Lin C-C; River J; River P; et al. Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of Chicago, Chicago, IL 60637, USA

This study of 74 diabetic pregnant women shows that tight maternal blood glucose control before the 32nd week of gestation significantly reduces the incidence of fetal macrosomia (11%) when compared with that of patients with fair to poor control before the 32nd week of gestation (44%, P less than .05) or with those whose good diabetic control was not achieved until after the 32nd week of gestation (34%, P less than .05). The macrosomic infant produced by a diabetic mother is associated frequently with an elevated amniotic fluid C-peptide level, which shows the evidence of intrauterine fetal hyperinsulinism. The use of tight diabetic control early in pregnancy to reduce the risk of fetal macrosomia and/or neonatal complications is of clinical importance in the management of diabetes in pregnancy.

Gastro-entero-pancreatic hormones in amniotic fluid from normal and diabetic pregnant women.

Clinical applications of analyses of hormones in amniotic fluid (AF) have recently been increased. In diabetic pregnancy, determinations of insulin and C-peptide in AF have been suggested as good indicators of the status of the foetus. We have investigated the pancreatic alpha and beta cell function by measuring insulin (IRI), C-peptide (CPR), glucagon (IRG), somatostatin (SLI), and gastric inhibitory polypeptide (GIP) in amniotic fluid collected during basal conditions or 2 h after an arginine test in 92 diabetic and 32 non-diabetic pregnant women. During basal conditions, in diabetic pregnant women, IRI, CPR and the insulin: glucagon molar ratio (I/G) were all significantly higher while amniotic fluid-IRG was significantly lower than in the controls. After arginine stimulation, IRI increased in AF of the diabetic pregnant women but not in AF of the controls while no differences were observed in AF-GIP and AF-SLI concentrations. Higher IRI and CPR, as well as lower IRG values were significantly related to poor maternal metabolic control. The occurrence of neonatal morbidity including macrosomia was significantly associated with increased AF, IRI and CPR concentrations after an arginine challenge and these factors were the most sensitive predictors of neonatal morbidity in infants of diabetic mothers. Increased AF glucose concentrations and I/G ratios were related to neonatal hypoglycaemia; jaundice and respiratory distress syndrome were associated to low concentrations of SF-IRG.

Interrelationship between amniotic fluid C-peptide and catecholamines in the last trimester of diabetic pregnancy

Amniotic fluid concentration and content (amniotic fluid volume × concentration) of C-peptide and catecholamines (epinephrine, norepinephrine) and their interrelationship was studied in nine women with gestational diabetes, in 14 women with type I diabetes, and in 20 healthy control women between the thirty-sixth and thirty-ninth week of gestation. Mean amniotic fluid volume was significantly larger (p < 0.05) in the type I diabetic group than in the control group. Mean concentration and content of amniotic fluid C-peptide were elevated in women with gestational diabetes, significantly so in women with type I diabetes (p < 0.05) as compared with nondiabetic control women. Mean amniotic fluid catecholamine concentrations were lower, although not statistically so, in both insulin-dependent and gestational diabetic women than in control women. Mean amniotic fluid catecholamine content was higher, although not statistically so, in women with gestational diabetes than in control women. In the type I diabetic group, epinephrine content was significantly lower (p < 0.05) and norepinephrine content significantly higher (p < 0.05) than in the control group. A significant positive correlation between the content of norepinephrine and C-peptide was found in control women (r = 0.57; p < 0.05) and in women with gestational diabetes (r = 0.75; p < 0.05). The close interrelationship could indicate a parallel maturation of these two hormonal systems.

Fetal insulin production and complications in babies of diabetic mothers

SummaryFetal pancreatic β-cell activity was studied by measuring amniotic fluid C-peptide and insulin concentrations by radio-immunoassay in 27 pregnancies. There were 9 non-diabetics, 9 well controlled diabetics and 9 poorly controlled diabetics.There was a correlation between C-peptide and insulin concentrations in the 27 patients. There was also a correlation between C-peptide and insulin concentration and maternal blood glucose levels.The study demonstrated a clear association between fetal hyperinsulinaemia and neonatal hypoglycaemia. Similarly, fetal macrosomia was significantly related to amniotic C-peptide and insulin levels.The relationship between insulin production and surfactant maturation in the fetus and the subsequent development of neonatal respiratory distress was less straightforward. It is thought that fetal insulin production in infants of diabetic mothers may not be primarily responsible for observed differences in surfactant maturation.

Spiral artery lesions in relation to metabolic control in diabetes mellitus.

Decidual and intramyometrial spiral arteries from 18 insulin-dependent diabetic and 18 non-diabetic women were compared histologically. All women were normotensive and none had signs of pre-eclampsia. None of the infants in either group had intra-uterine growth retardation. Metabolic control in the diabetic women was assessed by pregnancy glucose level from the last trimester of pregnancy and by C-peptide in amniotic fluid and cord blood as a measure of the fetal beta-cell function. The intramyometrial and decidual parts of the spiral artery were normal in the non-diabetic group. None of the diabetic patients showed pathological changes in the intramyometrial part of the spiral artery. Two of the 18 diabetic patients had pathological changes (intramural fibrosis) in the decidual portion of the spiral artery. These two women had signs of diabetic angiopathy (White's class D and F) and in one of them, the background diabetic retinopathy progressed markedly during pregnancy. The pregnancy glucose level was above normal (greater than 6.2 mM/l) in 3 of 18 diabetics. The C-peptide values in amniotic fluid and cord blood were above normal in 11 of 17 and in 5 of 17, respectively. Both patients with spiral artery lesions had pregnancy glucose levels in the upper range, 5.86 and 5.98 mM/l, respectively and the highest value of C-peptide in the amniotic fluid and cord blood, suggesting exaggerated fetal beta-cell function.

Amniotic fluid C-peptide and phosphatidyl glycerol in diabetic pregnancy.

The concentrations of C-peptide and phosphatidylglycerol in the amniotic fluid were determined in 36 pregnant diabetic women. Twenty-one patients who were being treated with insulin for gestational diabetes as well as 15 patients who were insulin dependent were studied. All patients were subjected to a program of strict metabolic control, and amniocentesis was performed at gestational week 36-37. Phosphatidyl glycerol was present in the amniotic fluid in 15 cases and absent in 21. The mean concentration of C-peptide did not differ whether phosphatidyl glycerol was present or absent. (C-peptide: 0.56 +/- 0.06 and 0.43 +/- 0.05 nmol/l respectively). Although the mean value for amniotic fluid C-peptide in both groups was close to that in diabetic pregnancies with an uneventful neonatal outcome, it was significantly higher than that in non-diabetic pregnancies, indicating minor fetal hyperinsulinemia. The level of C-peptide in the amniotic fluid showed a correlation to the subsequent birthweight of the infant (r = 0.50; p less than 0.01). It is concluded that with rigorous metabolic control of the pregnant diabetic patient, the presence or absence of phosphatidyl glycerol, as an index of fetal lung maturity, is apparently not related to the level of C-peptide in the amniotic fluid.

Fetal beta cell function in diabetic pregnancy: Amniotic fluid concentrations of proinsulin, insulin, and C-peptide during the last trimester of pregnancy

Proinsulin, insulin, C-peptide, insulin-binding antibody, and glucose concentrations were measured in amniotic fluid samples from 43 insulin-treated diabetic patients and 17 nondiabetic control patients between the thirty-sixth and thirty-ninth weeks of gestation. Insulin-binding antibodies in amniotic fluid were present in only three diabetic patients, although antibodies in maternal serum were found in 22 of the diabetic subjects. In the diabetic group, maternal serum insulin-binding antibodies were statistically unrelated to levels of C-peptide in amniotic fluid. The mean amniotic fluid concentrations of proinsulin (0.07 nmole/L), insulin (0.08 nmole/L), C-peptide (1.17 nmoles/L), and glucose (2.09 mmoles/L) were markedly elevated (p < 0.001) in diabetic patients, as compared to nondiabetic control patients, thus suggesting exaggerated fetal beta cell function. C-peptide was correlated to both insulin (r = 0.69) and proinsulin (r = 0.35) in the diabetic group only. Infant birth weight and amniotic fluid C-peptide was significantly correlated in both the control group (r = 0.54) and the diabetic group (r = 0.38). Diabetic pregnancies associated with neonatal morbidity (n = 25) had significantly higher mean amniotic fluid concentrations of both insulin and C-peptide than did pregnancies without neonatal morbidity (n = 18). The amniotic fluid values of C-peptide and insulin in these latter two subgroups were overlapping and, therefore, could not serve to predict neonatal outcome in the individual case.

Amniotic fluid C-peptide as an index for intrauterine fetal growth

Amniotic fluid C-peptide (AFCP) was monitored as an indicator of the amount of insulin secreted by the fetus in utero. Levels of amniotic fluid and cord blood C-peptide, insulin, and glucose were measured in 103 nondiabetic infants at ≥36 weeks' gestation. Infants were grouped according to birth weight and gestational age at delivery, as follows: small for gestational age (SGA, ≤10%, n = 11), average for gestational age (AGA, 10% to 90%, n = 75), large for gestational age (LGA, >90%, n = 17). AFCP correlated best with infant weight-gestational age percentile classification: low AFCP in SGA infants and high AFCP in LGA infants. The data from this study suggest that a persistently low production of insulin by SGA fetuses and a high production of insulin by LGA fetuses may lead to the different intrauterine growth rates observed.

Prenatal assessment of fetal outcome by amniotic fluid C-peptide levels in pregnant diabetic women

Amniotic fluid C-peptide (AFCP), insulin, and glucose levels were measured in 33 diabetic and 126 nondiabetic pregnant women at ≖36 weeks' gestation. Levels of AFCP distinguished diabetic from nondiabetic patients more reliably than amniotic fluid (AF) insulin or glucose. Levels of AFCP in diabetic patients correlated well with Infant birth weight adjusted for gestational ages(large for gestational age > adequate for gestational age), degree of diabetic control (fair to poor control > good control), or diabetogenic infant morbidity, but did not correlate, with classes of diabetes within the limits of the population studied. We conclude that AFCP is a usefull prognostic index tor predicting fetal outcome in diabetic pregnancies. A level of AFCP of ≖1.0 pmoles/ml is associated with an increased risk of macrosomia in infants of diabetic mothers. (Am. J. Obstet. Gynecol. 141:671, 1981.)

Amniotic fluid C-peptide in normal and insulin-dependent diabetic pregnancies.

Glucose, insulin and C-peptide were determined in amniotic fluid from 28 normal and 46 insulin-treated diabetic pregnant women. Glucose, insulin and C-peptide concentrations in amniotic fluid were higher in the diabetics than in the normal subjects. In diabetic women insulin levels did not correlate with birth weight or birth weight adjusted for gestational age, but C-peptide did. C-peptide correlated poorly with insulin (p < 0.05) in diabetics but closely (p < 0.002) in normal subjects. These results suggest that amniotic fluid investigations in insulin-treated diabetic women should use C-peptide assays as these seem to reflect more closely the insulin production of the fetus than do insulin assays. There were no differences in amniotic fluid glucose, insulin and C-peptide concentrations where the amniotic fluid lecithin-sphingomyelin ratio indicated fetal pulmonary maturity or immaturity.