[Significance of hormones in the amniotic fluid. 1. Insulin and C-peptide]

Samples of amniotic fluid of 275 healthy women were used to establish a standard profile of amniotic fluid insulin and C-peptide concentrations versus gestational age. The reasons for amniocentesis were: exclusion of chromosomal defects, rhesus immunisation, and determination of the L/S ratio. The concentrations of both peptides which were measured in the amniotic fluid in diabetics were compared with the normal profile. We found that long-term blood glucose control as estimated by the concentration of glycosylated haemoglobins in maternal blood is not well correlated with amniotic fluid insulin or C-peptide, respectively. In a few cases with poor metabolic control, we found normal insulin values, and vice versa. Since elevated insulin and C-Peptide levels in amniotic fluid correlate well with diabetic foetopathy, we conclude that measurement of both peptides provides a useful parameter in the management of a diabetic pregnancy.